Various refactorings to prepare proper big picture loading

 - Added a function to load a picture with ideal sampleSize
 - Renamed xmls/java files for tiles
 - ContactTileView is now abstract and has subclasses for each use-case
 - Added mechanism to estimate the image-size in a tile before layout
 - Changed the cross-fade in ContactPhotoManager to apply the fade to the
   current picture instead of the default avatar. Reduces flickering

Bug:6202229

Change-Id: Ic8636d1b3349473163fb2424b5f74476fd435fb5