Gracefully handle search failure in flickr sample
Update the comments in the Glide singleton
Add a BaseModelLoader

Allows us to remove the repetitive
ModelLoader.close() -> StreamOpener.cancel()
Clear loaders before load in ImagePresenter

Allows us not to call clear before new loads in
all of the loaders
update VolleyModelLoader to remove repeated code
Simplify the exception handler in ImagePresenter
Make compression quality to diskcache configurable

Also decrease the default from 100 to 90.
Javadoc fixes and updates