Don't log verbosely unless explicitly enabled
Fix a typo in the readme
Revert to holding strong references during loads

This fixes a bug where a load may silently fail to
complete if the user passes in a target and does
not retain a reference to the target for the 
duration of the load.
Allow match_parent/wrap_content view dimensions

By default if the view has wrap_content for either
the width or the height (or both), we will load
the image in at the original size. Trying to apply
either FitCenter or CenterCrop to the load will
still result in an exception since we would need
concrete sizes to transform the image.
add a few basic tests for ImagePresenter