Bundler gems installed from sources other than rubygems were breaking ocra build

Because of the way how gemspec files were calculated, ocra was breaking for gems that were installed via git or local path like this 

`gem 'spree', :git => 'git://github.com/spree/spree.git'`

Attached is a hacky patch to address such gems in the bundler file. 

Fixes the proper gemspec file and where the files need to be fetched from when.