This also removes Pry.

This test will generate a basic Rails application, include Paperclip
into Gemfile, and call basic `has_attached_file` in the model. This will
make sure that we're not messing up any of the configuration and
integration for our gem and the Rails framework.

However, this will make sure that you can always change it to something else afterward.

There's currently no test for this, but after I've tried this with the `integration_test` branch, I can confirm that logs are written to `log/test.log` as it should.

Closes #581

Abstract out the file geometry parser within Thumbnail. This makes it possible to have different cropping and scaling controls, as the papermill gem does.

Bump rails 3_1 version to rc6

Update Gemfile to make sure we can run the test locally, and also upgrade Rails 3.1 beta to latest version

This will fix the problem with Psych on the old version of Rails 2.x