Added map to open gem file by typing gm

Author: Aaron Baker

.vim/common_config/key_mappings.vim

@@ -17,6 +17,7 @@
 " shortcuts for frequenly used files
   nmap gs :e db/schema.rb<cr>
   nmap gr :e config/routes.rb<cr>
+  nmap gm :e Gemfile<cr>
 
 " insert blank lines without going into insert mode
   nmap go o<esc>