Reduce the odds of a collision in image keys

Fixes #27
Add an exception handler to Glide requests

Fixes #26
move key generator to its own class and add test
remove unused imports
Merge branch 'better_disk_cache_hash'
use the correct bitmap size in LruBitmapPool
remove an uneccessary exception
expose bitmap pool via ImageManager
Call recycle on bitmaps not added to bitmap pool.

Fixes #33.
Expand exception handler to listen to load completion
Introduced methods to trim and clear the memory cache
Memory cache adapter implements new methods
Skipping the bitmap pool if the image to be decoded is a GIF
Removed method from public api of memory cache
Recycling bitmaps when clearing cache
Merge remote-tracking branch 'shazam/shazam_memcache_trim_clear'
ignore inlined api for constants in LruMemoryCache
Merge branch 'add_exception_handler'

Conflicts:
	library/tests/src/com/bumptech/glide/GlideTest.java
Skipping pool for anything that is not png or jpg. This allows us to add more types in the future and they will skip the pool automatically
Fixed wrong boolean expression in determining whether to skip the pool or not