Include test results in short summary

We (@unknown-horizons) use a slightly different output for our IRC channel reports, that you might find useful. All changes were originally made by our team member @squiddy, I just keep rebasing them onto the new changes. A sample message comparison:

**Old** format:
```Project uh-tests build #3185: SUCCESS in 1 min 13 sec: http://ci.unknown-horizons.org/job/uh-tests/3185/```

**New** format:
```uh-tests #3186: SUCCESS [153/153] (0 failed ±0): http://ci.unknown-horizons.org/job/uh-tests/3186/```

The most noteworthy feature is probably displaying the number of changes, e.g. 5 more tests failed with this build in comparison to the last build.

In total it is shorter and includes more useful information (in our opinion). Feel free to merge if you find it useful or close the PR if you don't like the output format.

Thanks for the great work on the plugin!