Fix failing `rake test:integration`

I see the following failure under Ruby 2.0.0p195 and Bundler 1.3.5 on both Ubuntu 10.04 and Mac OS X 10.8.4. This patch addresses the problem. 

    $ rake test:integration
    Run options: --seed 35822

    # Running:

    ............F....

    Finished in 4.528087s, 3.7543 runs/s, 9.2754 assertions/s.

      1) Failure:
    GemcutterApiTest#test_method: can push example  [/Users/jfoy/src/geminabox/test/test_support/geminabox_test_case.rb:59]:
    Gemfile not in data dir.

    17 runs, 42 assertions, 1 failures, 0 errors, 0 skips
    rake aborted!
    Command failed with status (1): [ruby -I"lib:test:lib" -I"/Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib" "/Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/rake_test_loader.rb" "test/integration/**/*_test.rb" ]
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/testtask.rb:104:in `block (3 levels) in define'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/file_utils.rb:45:in `call'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/file_utils.rb:45:in `sh'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/file_utils_ext.rb:37:in `sh'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/file_utils.rb:82:in `ruby'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/file_utils_ext.rb:37:in `ruby'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/testtask.rb:100:in `block (2 levels) in define'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/file_utils_ext.rb:58:in `verbose'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/testtask.rb:98:in `block in define'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:246:in `call'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:246:in `block in execute'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:241:in `each'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:241:in `execute'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:184:in `block in invoke_with_call_chain'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:205:in `block in invoke_prerequisites'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:203:in `each'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:203:in `invoke_prerequisites'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:183:in `block in invoke_with_call_chain'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/task.rb:170:in `invoke'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:143:in `invoke_task'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:101:in `block (2 levels) in top_level'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:101:in `each'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:101:in `block in top_level'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:110:in `run_with_threads'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:95:in `top_level'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:73:in `block in run'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:160:in `standard_exception_handling'
    /Users/jfoy/src/geminabox/vendor/bundle/gems/rake-10.0.4/lib/rake/application.rb:70:in `run'
    Tasks: TOP => test => test:integration
    (See full trace by running task with --trace)