pull-request and review before merge methods

[barryk]

These two go hand-in-hand really. But the existing pull-request command is actually only generating text it's not doing a github pull-request. This renames the existing pull-request command to pull-request-text and adds a pull-request command to issue a github pull-request.

http://github.com/barryk/github-gem/tree/PullRequest

Additionally, a maintainer may be frequently pulling in branches, testing them, merging them, pushing back to github, or perhaps testing, failing, writing a message for why. This adds basic code review commands:
review
review-pass
review-fail
with usage such as:
github review OtherUser/BranchName

test test test

github review-fail

editor opens, type a response as to why you failed this

or

github review-pass

merges into master, and pushes master back to github.

http://github.com/barryk/github-gem/tree/ReviewBranch