We were using Godep incorrectly (cloning repos from the internet during
build time instead of including Godeps/_workspace in the GOPATH via
"godep go"). However, to avoid even having to fetch "godeps" from the
internet during build, this now just copies the vendored files into the
GOPATH.
Also, the protocol buffer library moved from Google Code to GitHub,
which is reflected in these updates.
This fixes https://github.com/prometheus/prometheus/issues/525
Julius Volz
Stuart Nelson