Fix failing travis build

This PR should fix error (see below) in travis build.
```
$ bundle exec rake appraisal:install && bundle exec rake appraisal spec
>> bundle install --gemfile=/home/travis/build/crafterm/comma/gemfiles/rails3.0.9.gemfile
/home/travis/.rvm/rubies/ree-1.8.7-2012.02/lib/ruby/site_ruby/1.8/rubygems/dependency.rb:296:in `to_specs': Could not find 'bundler' (>= 0) among 12 total gem(s) (Gem::LoadError)
```