Add Project#depend_on_rspec_rails?
Rename Project#require_bundler? to #using_bundler?
Use the same project instance consistently
Inject Project instance into SpecSuite
Inject Project instance into Syntax instance
Refactor syntax classes with the stored project instance
Check if rspec-rails is used with Gemfile when there's no runtime data
Add changelog entry
Merge branch 'check-whether-rspec-rails-is-used-via-gemfile'

This closes #88.