THRIFT-4448: Golang: do something with context.Context. Remove Go1.6 compatibility.
Client: go

This closes #1459
diff --git a/build/docker/ubuntu-trusty/Dockerfile b/build/docker/ubuntu-trusty/Dockerfile
index 40f9c55..a8e4d3b 100644
--- a/build/docker/ubuntu-trusty/Dockerfile
+++ b/build/docker/ubuntu-trusty/Dockerfile
@@ -113,9 +113,15 @@
 `# GlibC dependencies` \
       libglib2.0-dev
 
-RUN apt-get install -y --no-install-recommends \
-`# golang (go) dependencies` \
-      golang-go
+# golang
+ENV GOLANG_VERSION 1.7.6
+ENV GOLANG_DOWNLOAD_URL https://golang.org/dl/go$GOLANG_VERSION.linux-amd64.tar.gz
+ENV GOLANG_DOWNLOAD_SHA256 ad5808bf42b014c22dd7646458f631385003049ded0bb6af2efc7f1f79fa29ea
+RUN curl -fsSL "$GOLANG_DOWNLOAD_URL" -o golang.tar.gz && \
+      echo "$GOLANG_DOWNLOAD_SHA256  golang.tar.gz" | sha256sum -c - && \
+      tar -C /usr/local -xzf golang.tar.gz && \
+      ln -s /usr/local/go/bin/go /usr/local/bin && \
+      rm golang.tar.gz
 
 RUN apt-get install -y --no-install-recommends \
 `# Haskell dependencies` \