VOL-1460 Updated core to use voltha-protos instead of local protos
Moved protos to python directory in order to maintain functionaly of containers built there.
Added capability to do local builds of protos
Added instructions on running dep ensure for getting protos.
Updated github.com/golang/protobuf version to v1.3.1

Change-Id: Ia6ef55f07f0d5dcb5b750d7c37b21b71db85bfc4
diff --git a/vendor/github.com/golang/protobuf/proto/table_unmarshal.go b/vendor/github.com/golang/protobuf/proto/table_unmarshal.go
index ebf1caa..acee2fc 100644
--- a/vendor/github.com/golang/protobuf/proto/table_unmarshal.go
+++ b/vendor/github.com/golang/protobuf/proto/table_unmarshal.go
@@ -136,7 +136,7 @@
 		u.computeUnmarshalInfo()
 	}
 	if u.isMessageSet {
-		return UnmarshalMessageSet(b, m.offset(u.extensions).toExtensions())
+		return unmarshalMessageSet(b, m.offset(u.extensions).toExtensions())
 	}
 	var reqMask uint64 // bitmask of required fields we've seen.
 	var errLater error
@@ -362,46 +362,48 @@
 	}
 
 	// Find any types associated with oneof fields.
-	// TODO: XXX_OneofFuncs returns more info than we need.  Get rid of some of it?
-	fn := reflect.Zero(reflect.PtrTo(t)).MethodByName("XXX_OneofFuncs")
-	if fn.IsValid() {
-		res := fn.Call(nil)[3] // last return value from XXX_OneofFuncs: []interface{}
-		for i := res.Len() - 1; i >= 0; i-- {
-			v := res.Index(i)                             // interface{}
-			tptr := reflect.ValueOf(v.Interface()).Type() // *Msg_X
-			typ := tptr.Elem()                            // Msg_X
+	var oneofImplementers []interface{}
+	switch m := reflect.Zero(reflect.PtrTo(t)).Interface().(type) {
+	case oneofFuncsIface:
+		_, _, _, oneofImplementers = m.XXX_OneofFuncs()
+	case oneofWrappersIface:
+		oneofImplementers = m.XXX_OneofWrappers()
+	}
+	for _, v := range oneofImplementers {
+		tptr := reflect.TypeOf(v) // *Msg_X
+		typ := tptr.Elem()        // Msg_X
 
-			f := typ.Field(0) // oneof implementers have one field
-			baseUnmarshal := fieldUnmarshaler(&f)
-			tags := strings.Split(f.Tag.Get("protobuf"), ",")
-			fieldNum, err := strconv.Atoi(tags[1])
-			if err != nil {
-				panic("protobuf tag field not an integer: " + tags[1])
-			}
-			var name string
-			for _, tag := range tags {
-				if strings.HasPrefix(tag, "name=") {
-					name = strings.TrimPrefix(tag, "name=")
-					break
-				}
-			}
-
-			// Find the oneof field that this struct implements.
-			// Might take O(n^2) to process all of the oneofs, but who cares.
-			for _, of := range oneofFields {
-				if tptr.Implements(of.ityp) {
-					// We have found the corresponding interface for this struct.
-					// That lets us know where this struct should be stored
-					// when we encounter it during unmarshaling.
-					unmarshal := makeUnmarshalOneof(typ, of.ityp, baseUnmarshal)
-					u.setTag(fieldNum, of.field, unmarshal, 0, name)
-				}
+		f := typ.Field(0) // oneof implementers have one field
+		baseUnmarshal := fieldUnmarshaler(&f)
+		tags := strings.Split(f.Tag.Get("protobuf"), ",")
+		fieldNum, err := strconv.Atoi(tags[1])
+		if err != nil {
+			panic("protobuf tag field not an integer: " + tags[1])
+		}
+		var name string
+		for _, tag := range tags {
+			if strings.HasPrefix(tag, "name=") {
+				name = strings.TrimPrefix(tag, "name=")
+				break
 			}
 		}
+
+		// Find the oneof field that this struct implements.
+		// Might take O(n^2) to process all of the oneofs, but who cares.
+		for _, of := range oneofFields {
+			if tptr.Implements(of.ityp) {
+				// We have found the corresponding interface for this struct.
+				// That lets us know where this struct should be stored
+				// when we encounter it during unmarshaling.
+				unmarshal := makeUnmarshalOneof(typ, of.ityp, baseUnmarshal)
+				u.setTag(fieldNum, of.field, unmarshal, 0, name)
+			}
+		}
+
 	}
 
 	// Get extension ranges, if any.
-	fn = reflect.Zero(reflect.PtrTo(t)).MethodByName("ExtensionRangeArray")
+	fn := reflect.Zero(reflect.PtrTo(t)).MethodByName("ExtensionRangeArray")
 	if fn.IsValid() {
 		if !u.extensions.IsValid() && !u.oldExtensions.IsValid() {
 			panic("a message with extensions, but no extensions field in " + t.Name())
@@ -1948,7 +1950,7 @@
 // If there is an error, it returns 0,0.
 func decodeVarint(b []byte) (uint64, int) {
 	var x, y uint64
-	if len(b) <= 0 {
+	if len(b) == 0 {
 		goto bad
 	}
 	x = uint64(b[0])