[spec] Fixed broken spec.

* Fixtures are now included again.
* Extended stub for new functionality.
@mention users in hipchat message, when configured.
Hipchat message now also reports the url for details.

New output:
"[My Project] my bucket failed (build: very lon.2342; xy://somewhere/project/show_build/1234)."
Cleaned up hipchat message.

* No longer show build with short_identifier, since the url already provides this information.
* New output looks something like this:

[Cloud Connector] scrival:test:integration failed - https://dcc.infopark.de/project/show_bucket/46093 /cc @apepper