Make Rg and Rgem open Gemfile

Right now to get the the Gemfile you can either do Rlib (with no parameters) or R Gemfile. 

This is okay, but I'd prefer to have a shortcut for this, something like Rgem and/or Rg. Rlib is short, but it's not named properly.

I know it's a small thing, but it bothers me because I go to the Gemfile a lot. It would be nice to have a shortcut. 

What do you think?