Adds a wrapper for the ImageLoader library

:x:

@charroch the app is in a state where ImageLoader can be integrated. Comments, suggestions and PRs are welcome here.

API-wise, I think @frankiesardo is right, the first thing to do is get rid of the ImageTag and ImageTagFactory.
@mr-archano had some comments on how bitmaps are decoded (there's an open issue on this too which Carl has responded to).

If anyone wants the imgur API key, I can email it :)