rails_gemfile_entry and database_gemfile_entry return objects in rails 4.1, so deal with that
weirdly rails-api will run `spring binstub --all` and fail because it isn't in the gemfile, while vanilla rails doesn't run it at all. no idea why, but tell it to add spring explicitly for now
Added initial support for rails 4.1
Merge pull request #131 from RMaksymczuk/fix_gemfile_generation_4.1

Fix gemfile generation 4.1