Merge pull request #219 from justinstoller/gemsource

allow specifying gem source via env var

Gemfile

@@ -1,4 +1,4 @@
-source 'https://rubygems.org'
+source ENV['GEM_SOURCE'] || 'https://rubygems.org'
 
 group :development, :test do
   gem 'rake',                    :require => false