WIP: Differential Rotation Image Warp

This is a first pass at implementing a differential  correction to images. Currently it computes the full transform for all pixels in an image (yes even SDO) and then does a warp. (The slow part is the wcs transforms)

TODO:
- [ ] Test current implementation
- [ ] Test for something other than AIA
- [ ] Implement a routine that dosen't compute every pixel
- [ ] Write tests

For a example of this implementation see: http://nbviewer.ipython.org/6763463