Add gemrc dotfile

Don't install ri or rdoc docs for Rubygems by default.
Update color scheme in vimrc.

color-schemes bundle doesn't seem to be working correctly right now. Use
Molokai bundle instead.

Removed custom Monokai color scheme as molokai works better.
Fix bash_profile template.

input_prompt (which was an old helper method) was being called. That
function doesn't exist anymore, so it was failing and returning an empty
.bash_profile. Use the input method from the Six library instead.
Tmux colors in Linux.

Added some custom color settings back into the Linux tmux config.
.bash.d directory for Linux.

I use .bash.d directory to load various scripts instead of
.bash_profile becoming a huge mess. Added it for Linux with an rbenv
script.