fix nre on getImmediateMutableDrawable. need to rename this function to something not stupid,
Major refactor:
Instead of caching Drawables, cache the actual bitmaps themselves.
This was necessary, because Drawables are mutated via their corresponding ImageViews
via setBounds etc.
For example, if an ImageView scales a drawable down, this has the effect of scaling
the drawawble down for all other ImageViews using the same drawable.
By caching bitmaps, and refcounting using the finalizer, unique Bitmap/ZombieDrawable
instances can be used. Under the hood, the Bitmap is still cached and used
by multiple Drawables.

There were also breaking API changes (regarding loaders and callbacks) that could not
be avoided without gimping the API.
Change getBitmap to the more accurate description getCachedBitmap.
prevent redundant ZombieDrawable allocation
ZombieDrawable info
post refactor fixups around bitmap caching and callbacks
Take the max age of a file in account. #51
Dont use junit.framework.Assert#assert. User assert() instead.
Dont use junit.framework.Assert#assert. User assert() instead.
Merge pull request #55 from ChristianBecker/noUnitAsserts

Dont use junit.framework.Assert#assert. Use assert() instead.
Merge pull request #54 from ChristianBecker/master

cleanup: Take the age parameter in account
Merge remote-tracking branch 'upstream/master' into maven

Conflicts:
	UrlImageViewHelper/src/com/koushikdutta/urlimageviewhelper/UrlImageViewHelper.java
Update version.