Support the Go compiler on all arches, not just amd64.
This switches from using Google's pre-built binaries to using our archive builds of Google's compiler, thus giving us all platforms we support. And matching what we do for Python and Java.
Since this means we use whichever version of Go the host platform has, I've dropped the "1.4" from the plugin names.
I've tested this on wily and trusty. by mterry approved by sergiusens