Include shared Gemfile

In our apps we have a [git] submodule for shared models, mixins, etc.

Off course, these come with their own gem dependencies. In order to make sure these gems are up-to-date in all the apps we apply the following hack.

# Gemfile
source 'https://rubygems.org'

# include the Gemfile from the shared submodule
eval File.read File.expand_path('../shared/Gemfile', __FILE__)

gem 'rails', '3.2.16'
# etc, etc,