Add Ember 1.1.0 to Appraisal

This PR changes the following:

* Add an entry for `ember-source-1.1.0` for Rails 3.1, 3.2, and 4.0.
* Ignore Gemfile.lock files generated by Appraisal (they change everytime).
* Makes the default development dependency of `ember-source-1.1.0`.
* Removes Appraisals for pre-release versions of Ember (specifically: RC2, RC3, RC5, RC6.4, RC7, and RC8).