[VOL-2193] Create mocks for Kafka Client and Etcd

This commit consists of:
1) A kafka client mock that implements the kafka client interface
under voltha-lib-go/pkg/kafka/client.go
2) An embedded Etcd server that runs in-process and represents an
Etcd server.

Change-Id: I52a36132568e08c596bb4136918bebcb654a3b99
diff --git a/vendor/github.com/json-iterator/go/iter_int.go b/vendor/github.com/json-iterator/go/iter_int.go
new file mode 100644
index 0000000..2142320
--- /dev/null
+++ b/vendor/github.com/json-iterator/go/iter_int.go
@@ -0,0 +1,345 @@
+package jsoniter
+
+import (
+	"math"
+	"strconv"
+)
+
+var intDigits []int8
+
+const uint32SafeToMultiply10 = uint32(0xffffffff)/10 - 1
+const uint64SafeToMultiple10 = uint64(0xffffffffffffffff)/10 - 1
+
+func init() {
+	intDigits = make([]int8, 256)
+	for i := 0; i < len(intDigits); i++ {
+		intDigits[i] = invalidCharForNumber
+	}
+	for i := int8('0'); i <= int8('9'); i++ {
+		intDigits[i] = i - int8('0')
+	}
+}
+
+// ReadUint read uint
+func (iter *Iterator) ReadUint() uint {
+	if strconv.IntSize == 32 {
+		return uint(iter.ReadUint32())
+	}
+	return uint(iter.ReadUint64())
+}
+
+// ReadInt read int
+func (iter *Iterator) ReadInt() int {
+	if strconv.IntSize == 32 {
+		return int(iter.ReadInt32())
+	}
+	return int(iter.ReadInt64())
+}
+
+// ReadInt8 read int8
+func (iter *Iterator) ReadInt8() (ret int8) {
+	c := iter.nextToken()
+	if c == '-' {
+		val := iter.readUint32(iter.readByte())
+		if val > math.MaxInt8+1 {
+			iter.ReportError("ReadInt8", "overflow: "+strconv.FormatInt(int64(val), 10))
+			return
+		}
+		return -int8(val)
+	}
+	val := iter.readUint32(c)
+	if val > math.MaxInt8 {
+		iter.ReportError("ReadInt8", "overflow: "+strconv.FormatInt(int64(val), 10))
+		return
+	}
+	return int8(val)
+}
+
+// ReadUint8 read uint8
+func (iter *Iterator) ReadUint8() (ret uint8) {
+	val := iter.readUint32(iter.nextToken())
+	if val > math.MaxUint8 {
+		iter.ReportError("ReadUint8", "overflow: "+strconv.FormatInt(int64(val), 10))
+		return
+	}
+	return uint8(val)
+}
+
+// ReadInt16 read int16
+func (iter *Iterator) ReadInt16() (ret int16) {
+	c := iter.nextToken()
+	if c == '-' {
+		val := iter.readUint32(iter.readByte())
+		if val > math.MaxInt16+1 {
+			iter.ReportError("ReadInt16", "overflow: "+strconv.FormatInt(int64(val), 10))
+			return
+		}
+		return -int16(val)
+	}
+	val := iter.readUint32(c)
+	if val > math.MaxInt16 {
+		iter.ReportError("ReadInt16", "overflow: "+strconv.FormatInt(int64(val), 10))
+		return
+	}
+	return int16(val)
+}
+
+// ReadUint16 read uint16
+func (iter *Iterator) ReadUint16() (ret uint16) {
+	val := iter.readUint32(iter.nextToken())
+	if val > math.MaxUint16 {
+		iter.ReportError("ReadUint16", "overflow: "+strconv.FormatInt(int64(val), 10))
+		return
+	}
+	return uint16(val)
+}
+
+// ReadInt32 read int32
+func (iter *Iterator) ReadInt32() (ret int32) {
+	c := iter.nextToken()
+	if c == '-' {
+		val := iter.readUint32(iter.readByte())
+		if val > math.MaxInt32+1 {
+			iter.ReportError("ReadInt32", "overflow: "+strconv.FormatInt(int64(val), 10))
+			return
+		}
+		return -int32(val)
+	}
+	val := iter.readUint32(c)
+	if val > math.MaxInt32 {
+		iter.ReportError("ReadInt32", "overflow: "+strconv.FormatInt(int64(val), 10))
+		return
+	}
+	return int32(val)
+}
+
+// ReadUint32 read uint32
+func (iter *Iterator) ReadUint32() (ret uint32) {
+	return iter.readUint32(iter.nextToken())
+}
+
+func (iter *Iterator) readUint32(c byte) (ret uint32) {
+	ind := intDigits[c]
+	if ind == 0 {
+		iter.assertInteger()
+		return 0 // single zero
+	}
+	if ind == invalidCharForNumber {
+		iter.ReportError("readUint32", "unexpected character: "+string([]byte{byte(ind)}))
+		return
+	}
+	value := uint32(ind)
+	if iter.tail-iter.head > 10 {
+		i := iter.head
+		ind2 := intDigits[iter.buf[i]]
+		if ind2 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value
+		}
+		i++
+		ind3 := intDigits[iter.buf[i]]
+		if ind3 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*10 + uint32(ind2)
+		}
+		//iter.head = i + 1
+		//value = value * 100 + uint32(ind2) * 10 + uint32(ind3)
+		i++
+		ind4 := intDigits[iter.buf[i]]
+		if ind4 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*100 + uint32(ind2)*10 + uint32(ind3)
+		}
+		i++
+		ind5 := intDigits[iter.buf[i]]
+		if ind5 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*1000 + uint32(ind2)*100 + uint32(ind3)*10 + uint32(ind4)
+		}
+		i++
+		ind6 := intDigits[iter.buf[i]]
+		if ind6 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*10000 + uint32(ind2)*1000 + uint32(ind3)*100 + uint32(ind4)*10 + uint32(ind5)
+		}
+		i++
+		ind7 := intDigits[iter.buf[i]]
+		if ind7 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*100000 + uint32(ind2)*10000 + uint32(ind3)*1000 + uint32(ind4)*100 + uint32(ind5)*10 + uint32(ind6)
+		}
+		i++
+		ind8 := intDigits[iter.buf[i]]
+		if ind8 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*1000000 + uint32(ind2)*100000 + uint32(ind3)*10000 + uint32(ind4)*1000 + uint32(ind5)*100 + uint32(ind6)*10 + uint32(ind7)
+		}
+		i++
+		ind9 := intDigits[iter.buf[i]]
+		value = value*10000000 + uint32(ind2)*1000000 + uint32(ind3)*100000 + uint32(ind4)*10000 + uint32(ind5)*1000 + uint32(ind6)*100 + uint32(ind7)*10 + uint32(ind8)
+		iter.head = i
+		if ind9 == invalidCharForNumber {
+			iter.assertInteger()
+			return value
+		}
+	}
+	for {
+		for i := iter.head; i < iter.tail; i++ {
+			ind = intDigits[iter.buf[i]]
+			if ind == invalidCharForNumber {
+				iter.head = i
+				iter.assertInteger()
+				return value
+			}
+			if value > uint32SafeToMultiply10 {
+				value2 := (value << 3) + (value << 1) + uint32(ind)
+				if value2 < value {
+					iter.ReportError("readUint32", "overflow")
+					return
+				}
+				value = value2
+				continue
+			}
+			value = (value << 3) + (value << 1) + uint32(ind)
+		}
+		if !iter.loadMore() {
+			iter.assertInteger()
+			return value
+		}
+	}
+}
+
+// ReadInt64 read int64
+func (iter *Iterator) ReadInt64() (ret int64) {
+	c := iter.nextToken()
+	if c == '-' {
+		val := iter.readUint64(iter.readByte())
+		if val > math.MaxInt64+1 {
+			iter.ReportError("ReadInt64", "overflow: "+strconv.FormatUint(uint64(val), 10))
+			return
+		}
+		return -int64(val)
+	}
+	val := iter.readUint64(c)
+	if val > math.MaxInt64 {
+		iter.ReportError("ReadInt64", "overflow: "+strconv.FormatUint(uint64(val), 10))
+		return
+	}
+	return int64(val)
+}
+
+// ReadUint64 read uint64
+func (iter *Iterator) ReadUint64() uint64 {
+	return iter.readUint64(iter.nextToken())
+}
+
+func (iter *Iterator) readUint64(c byte) (ret uint64) {
+	ind := intDigits[c]
+	if ind == 0 {
+		iter.assertInteger()
+		return 0 // single zero
+	}
+	if ind == invalidCharForNumber {
+		iter.ReportError("readUint64", "unexpected character: "+string([]byte{byte(ind)}))
+		return
+	}
+	value := uint64(ind)
+	if iter.tail-iter.head > 10 {
+		i := iter.head
+		ind2 := intDigits[iter.buf[i]]
+		if ind2 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value
+		}
+		i++
+		ind3 := intDigits[iter.buf[i]]
+		if ind3 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*10 + uint64(ind2)
+		}
+		//iter.head = i + 1
+		//value = value * 100 + uint32(ind2) * 10 + uint32(ind3)
+		i++
+		ind4 := intDigits[iter.buf[i]]
+		if ind4 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*100 + uint64(ind2)*10 + uint64(ind3)
+		}
+		i++
+		ind5 := intDigits[iter.buf[i]]
+		if ind5 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*1000 + uint64(ind2)*100 + uint64(ind3)*10 + uint64(ind4)
+		}
+		i++
+		ind6 := intDigits[iter.buf[i]]
+		if ind6 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*10000 + uint64(ind2)*1000 + uint64(ind3)*100 + uint64(ind4)*10 + uint64(ind5)
+		}
+		i++
+		ind7 := intDigits[iter.buf[i]]
+		if ind7 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*100000 + uint64(ind2)*10000 + uint64(ind3)*1000 + uint64(ind4)*100 + uint64(ind5)*10 + uint64(ind6)
+		}
+		i++
+		ind8 := intDigits[iter.buf[i]]
+		if ind8 == invalidCharForNumber {
+			iter.head = i
+			iter.assertInteger()
+			return value*1000000 + uint64(ind2)*100000 + uint64(ind3)*10000 + uint64(ind4)*1000 + uint64(ind5)*100 + uint64(ind6)*10 + uint64(ind7)
+		}
+		i++
+		ind9 := intDigits[iter.buf[i]]
+		value = value*10000000 + uint64(ind2)*1000000 + uint64(ind3)*100000 + uint64(ind4)*10000 + uint64(ind5)*1000 + uint64(ind6)*100 + uint64(ind7)*10 + uint64(ind8)
+		iter.head = i
+		if ind9 == invalidCharForNumber {
+			iter.assertInteger()
+			return value
+		}
+	}
+	for {
+		for i := iter.head; i < iter.tail; i++ {
+			ind = intDigits[iter.buf[i]]
+			if ind == invalidCharForNumber {
+				iter.head = i
+				iter.assertInteger()
+				return value
+			}
+			if value > uint64SafeToMultiple10 {
+				value2 := (value << 3) + (value << 1) + uint64(ind)
+				if value2 < value {
+					iter.ReportError("readUint64", "overflow")
+					return
+				}
+				value = value2
+				continue
+			}
+			value = (value << 3) + (value << 1) + uint64(ind)
+		}
+		if !iter.loadMore() {
+			iter.assertInteger()
+			return value
+		}
+	}
+}
+
+func (iter *Iterator) assertInteger() {
+	if iter.head < len(iter.buf) && iter.buf[iter.head] == '.' {
+		iter.ReportError("assertInteger", "can not decode float as int")
+	}
+}