Fixed and added a few thingies

- bug: invalid import caused compilation issues
- bug: keep the callback so more data can be pushed through the same callback
- bug: `stopListening` was missing the last argument for the JS-Native bridge
- enhancement: don't report beacons with unknown states (`avoidUnknownStateBeacons`)
- enhancement: added human readable color to beacon result
- enhancement: added batterylevel (if reported) to beacon result
- cleanup: readme typo's and commented android block in plugin.xml