Card 16 (Zoom In/ Zoom out gesture at gallery)
- GalleryFragment: added mPhotosGridOnTouchListener field
- GalleryFragment: areplaced rebuild photos grid code with the call of
rebuildPhotosGrid method in the onGlobalLayout method of
photosGridListener in the refresh method
- GalleryFragment: added mPhotosGridOnTouchListener initalization and
setting to the photosGrid in the refresh method
- GalleryFragment: added new method rebuildPhotosGrid 
- GalleryFragment.PhotosGridOnTouchListener: added
- ScalableListView: added
- ImageFlowUtils: added additional checks to the buildGroups method to
skip rebuilding
- res/layout/fragment_gallery.xml: replaces ListView with
ScalableListView
- project.properties: replaces \\ with /