[Ch20 - chal.1 completed] Added support for orientation

Added:
+ Support for orientation, this allows images to appear properly
rotated on resulting ImageViews

Notes:
+ We used matrix rotation and set the subsampled bitmap into a new
bitmap with the matrix applied
+ But for some reason, the matrix rotation angle seems reversed (see
PictureUtils.java - line 61-65)

To-do:
+ Challenge #2