Using new android gradle plugin and buildtools. fixed an error that was discovered via travis.
Fixed #45

* extracted about fragment
* added open source note
* simplified about screen
* restructured license notes
Extracted OpenCorePlayRunnable.java
Refactored OpenCorePlayRunnable.java
Extreacted some Exceptions and OpencorePlayerProfilingInfo.java
Better Exception inheritance
Using DummyPlayerCallback instead of null check
Merged break conditions
executed "reformat" and "optimize imports"