VOL-546 Add support for proxy servers in build

- Propagate proxy environment variables into docker builds
- Generate mvn settings.xml based on proxy env vars and allow custom xml
- Update to latest docker installation within go-lang docker image (to avoid apt-key proxy issue)
- Allow additional parameters with DOCKER_BUILD_EXTRA_ARGS, for example --no-cache, --pull
- Also fixes 'overriding recipe for target' for voltha target

Change-Id: Ifa545a0262ecfe434ad230ddab4f61935c7244e0
(cherry picked from commit e0c9acbbd529b38da0adacdb6701cb0e37553119)
diff --git a/envoy/go/envoyd/build_binary.sh b/envoy/go/envoyd/build_binary.sh
index 1772809..037ebd8 100755
--- a/envoy/go/envoyd/build_binary.sh
+++ b/envoy/go/envoyd/build_binary.sh
@@ -2,7 +2,7 @@
 
 rm -fr buildreport
 rm -f envoyd
-docker run -v $(pwd):/src go-builder
+docker run -e "http_proxy=$http_proxy" -e "https_proxy=$https_proxy" -v $(pwd):/src go-builder
 #/build.sh
 uid=`id -u`
 gid=`id -g`