Change GOPATH from gerrit.opencord.org to github.com/opencord

Ran `go fmt` which did some line reordering after this change

Conformed Makefile to template the imagename and use correct DOCKER_*
build variables

Change-Id: I52734e805698b305cf64eb9238b08f152f68ffd4
diff --git a/core/openolt_service.go b/core/openolt_service.go
index 489e185..fafe1c9 100644
--- a/core/openolt_service.go
+++ b/core/openolt_service.go
@@ -19,9 +19,9 @@
 import (
 	"time"
 
-	"gerrit.opencord.org/voltha-bbsim/common/logger"
-	"gerrit.opencord.org/voltha-bbsim/device"
-	openolt "gerrit.opencord.org/voltha-bbsim/protos"
+	"github.com/opencord/voltha-bbsim/common/logger"
+	"github.com/opencord/voltha-bbsim/device"
+	openolt "github.com/opencord/voltha-bbsim/protos"
 )
 
 func sendOltIndUp(stream openolt.Openolt_EnableIndicationServer, olt *device.Olt) error {