Consistent animations & up button behavior in Gallery

Bug: 7302857
Bug: 7295464
This CL makes all of the transition animations throughout
the Gallery app consistent. The animation is the previous
view shrinking and fading out while the new view starts out
bigger than the view port and is coming in to the viewport
size as it fades in. Having consistent animations allows us
to not keep PhotoPage/AlbumPage instances around in certain
cases, making it possible to have consistent up button
behavior when switching between the grid and filmstrip.
Finally, this also makes the transitions in the camera app
filmstrip/grid switching consistent with those in the
gallery app.
Change-Id: I77bac6a0cde1e439738c78f9e16ab15ed5910cfb