I played around with publiclab's Leaflet.DistortableImage plugin for a georectification task I am working on. This is just a basic proof of concept to test out usability.
This uses a legacy version of Leaflet, unforunately (0.7.x). There is a pull request on Github to resolve this problem, but as of 11/4/2016 it had not been merged in.
This also uses leaflet-toolbar.
This is the main dependency used for this test app: https://github.com/publiclab/Leaflet.DistortableImage