* renamed VideoInfoItem to VideoPreviewInfo
* moved streaming service-related classes into their own, new package services
* added javadoc to some classes and methods (where functionality is known well enough to explain)
* De-duplicated common fields between VideoInfo and VideoPreviewInfo by moving them into a common superclass: AbstractVideoInfo
* Removed 2 methods which only call super(), and therefore are unnecessary: PlayVideoActivity.onResume() and PlayVideoActivity.onPostCreate(Bundle)
Conflicts:
app/src/main/java/org/schabi/newpipe/VideoItemDetailFragment.java -- still used class-based passing
app/src/main/java/org/schabi/newpipe/VideoItemListActivity.java -- just some whitespace
- made "could not find a streamingplayer" thing inside ActionBarHandler yield stacktraces
- remove watermark
- fixed fab layout
- changed version number to 0.5.0