Renames DummyVC to TRGridVC. Refs gradha/theranking-ios-candidates#4.
Adds dummy collection view and cells. Refs gradha/theranking-ios-candidates#4.
Adds cell information for each photo. Refs gradha/theranking-ios-candidates#4.

Also changes the grid size to 94pt so that text names fit better as
overlays. For megaiphone fizes a different cell size could be calculated
at runtime.
Adds cell interaction method. Refs gradha/theranking-ios-candidates#4.
Merge branch 'feature/t4_thumbnail_view' into develop