Pet opt-in

[ForNeVeR]

After this change, horta administrator will have to explicitly enable pet for the rooms where he wants to use it.

That's actually a breaking change, but we're still in major version 0, so we're allowed to make such changes without incrementing the major version.

Closes #400.

[ForNeVeR]

I need to investigate the failing tests. According to my current experiments, they are failing seemingly at random. Will report back after the investigation.

[hagane]

I know that failing test. It's failing because it has a seemingly arbitrary timeout. You can safely ignore it or, if you're serious about it, set it to not run in parallel with other test suites.

[hagane]

The test you added -- the one in PetPluginSpec -- looks genuinely broken, though.

[ForNeVeR]

Got it. Our static configuration is not the best candidate to be mocked during the unit tests. The problem is it gets configured only once per all the tests, and the resulting configuration is baked into static Configuration.properties object first time it's accessed.

I'll add some logic to globally deinitialize it for now, but we'll need to invent something more testable in the future (so we could replace or mock that configuration object on a per-plugin basis). Will file an issue for that.

[ForNeVeR]

Ah, I've just added these lines to the global config. It was the easiest way.

[rexim]

This is pretty good shit! I like it! Approved.

[ForNeVeR]

Thanks all. Will merge and release the new version soon.