Changed the notification format

I think the most important part, the commit message, was missing previously.
I also removed some less important parts, the repository will probably stay
the same and the travis build number is included in the build details link.

Before:
cantino/huginn#533 (master - 079b02f : Andrew Cantino): The build passed.
After:
\<Andrew Cantino> master - 079b02f (Some random commit message): The build passed.