Updated Makefile for Go 1.3+

Could not run "make rpm" with Go 1.3 due to grep regex.  Fix grep for future.
Fwiw, I used pessimistic matching ("only 1.1 or 1.2") because I don't trust Go not to break things, and that mistrust was validated when Go 1.3 was released, so I'm not likely to trust go 1.4, so we will continue to only update this regexp specific to versions of Go which are known and tested to work, which Go 1.3 is not at this time (but will, soon!)