More Intuitive Image Picker Implementation

[fennifith]

Currently, if your application overrides the default Application class, you must make your application's application class override the 'ColorPicker' application from this library in order for the image picker to function correctly. It might be better to instead replace this with an interface that can be passed to the dialog to notify it of activity results, to allow for more customization of how the dialog works.

[fennifith]

This picker is actually going to be absent from the 0.1.0 release because I'm lazy. It needed a rewrite anyway.