Fix empty commits and non-descript revert messages

  * Empty commits via editor now have the message: "[no message]"
  * Reverts now have the slightly more useful message: "Revert commit #1234567"
Merge pull request #644 from dekimsey/empty-commit-612

Fix empty commits and non-descript revert messages (For #612)
Fix #645
Merge pull request #646 from bootstraponline/master

Fix #645