more agressive image management

changes to better handle images.

-now the note detail view thumbnail is made purposefully small (just
big enough)
-resizing and saving smaller images to core data (may need to play with
for larger screen sizes)
-changed how resizing occrs to use core graphics
-more aggressive release of data (image and otherwise) after upload

the result: instead of hard crashing after taking ~8 photos, we hard
crash after ~36 photos. better, still not completely solved but maybe
(hopefully) pushed beyond the scope of 'normal' use.