0.2.2 Fix: Aborts if WP version unsupported, etc.

* Fixed: Aborts if WordPress version is unsupported
* Minimum WordPress version changed to 3.3.0, according to
[Plugin-Datei Doktor](http://de.wpseek.com/pluginfilecheck/)
* Added `LICENSE.txt` and `LICENSE.md` from [TheFox /
GPLv3.md](https://github.com/TheFox/GPLv3.md)