Remove ruby env files

Hackerpress should work on ruby 1.9.3+.
Specifying rvmrc settings is a bit annoying on dev boxes if the version of ruby is not installed.
Update travis to include ruby 2.0.0
Remove gem versions

This allows for the latest gems to be used by default. Travis should catch if any compatibility problems arise. Basically, the philosophy for hackerpress is to make it as easy as possible to hack. So by default, we'll loosen requirements as much as possible.