Restore window-crop*-route.

Restore window-crop-route and window-crop-fixed-route. Many of the
existing extensions use the ImageServing interface which generates
thumbnails of this form.
Add :image-type to routes and update handling

Add :image-type to the window-crop* routes. Re-added the route handling
logic back to app-routes.
Change mode to window-crop-fixed.
Fix the test for window-crop-fixed.
Fix route tests for window-crop*.

/cc @nmonterroso
Merge pull request #30 from Wikia/add-back-window-crop

Restore window-crop*-routes to support the thumbnail generation from ImageServing in MW