Add rvm configuration files to gitignore
Add rvm configuration files to gitignore

rvm users frequently use `.ruby-version`, `.ruby-gemset`, or `.rvmrc` (legacy) files to configure rvm and it's a Bad Practice™ to commit them. This will help prevent that for those folks.
robwierzbowski/generator-jekyllrb,robwierzbowski/generator-jekyllrb,robwierzbowski/generator-jekyllrb