Adds testfile helper methods
Adds testfiles dir
Fix testfile handling
Add aliases helper method to CLI

Allows creation of gem_polish aliases at a given destination with a
custom prefix, that defaults to gp
Add skeleton for gem manipulation
Add additional rspec configuration
Set up Gem CLI
First methods of gem add command
Finish basic options of gem add
Add spec for multiple options to gem add
Refactor and adding multiple gems at once
Add block creation for multiple gems in gem add