Rails 3.1.x has code which checks which version of ruby is being run,
and based on the result, selects a version of turn.
For 1.9.3+, it selects "~> 0.8.3"; for everything else, it selects "0.8.2".
If we remove turn from the Appraisals, but have travis install both versions
that rails might potentially need, the in-generated-app Gemfile building should
work correctly.
Some features test the factory_girl_rails integration with minitest-rails.
Other features just test normal integration with rails generators.
When minitest-rails is *always* in our gemfiles, minitest's generator
gets run during the features which generate new rails apps.
Because minitest doesnt support namespaced models, this fails. But, also,
we don't actually want to run minitest during anything other than the specific
areas where we are testing that integration.
Thus, we need the gem present on the system, but not in the gemfiles during
any times other than when it's pulled in specifically by those features.
