Refactor Git-Review.
Merge pull request #55 from xystushi/prepare_pull_request

Refactor Git-Review.
Remove newline from error message.
Only build in Ruby 1.9.3 and 2.0.0.
Run specs as rake's default task. Don't check in Gemfile.lock.
The right key is access_token in Octokit::Client.
Check args before calling shift on it.
Add support to send pull request to upstream repo.