Merge branch 'develop'
Update thor dependency to allow version 0.16.0

Version constraint also allows any yet-to-be-released 1.x version of
Thor, which will be backward compatible with current releases.
mocha 0.13.0 changed their api, let's stick with 0.12.7 for now
Added support for Pushover
Merge pull request #372 from sferik/update_thor

Update thor dependency to allow version 0.16.0
Merge pull request #381 from SteveNewson/pushover

Add support for notifying via Pushover.
Updated the README:

* Mention the Pushover notifier.
* Added contributor.
* Cleaned up other parts of the README.
The :version => 2 option has been deprecated by Guard.
Releasing version 3.0.26.
Merge branch 'develop'
Releasing version 3.0.27.