WIP: Update golang version to 1.7.1

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/Dockerfile.build

@@ -1,4 +1,4 @@
-FROM golang:1.5.4
+FROM golang:1.7.1
 RUN apt-get update && apt-get -y install iptables
 
 RUN go get github.com/tools/godep \