Add go commands and runtime into Dockerfile.
Add go commands and runtime into Dockerfile.

Right now pipeline doesn't have to have go for the code generation,
but Ic11e3ef603120bc7999731db549851c148943695 will use gofmt
command.

apt-get installs quite an old version of go (1.2.1 as I tried),
I feel it's better to use newer one, and installing through
linuxbrew would be a good choice to track the new version
automatically.

Change-Id: I8f34b5fba6294c81f54e219cd8183ed37131dafd

googleapis/artman,shinfan/artman,googleapis/artman,googleapis/artman,ethanbao/artman,ethanbao/artman