Use Octokit for authorization and fix 2FA bug.
Stub configure_oauth to ensure pass in Travis.
Fix #88, allow [tag] in commit message.
Merge pull request #87 from xystushi/simplify_login_and_2fa

Use Octokit for authorization and fix 2FA bug.
Bug in git-review clean command

number arg was nil (shifted twice)
Merge pull request #90 from xystushi/allow_tag_in_commit

Fix #88, allow [tag] in commit message.