Initiated an extensive rewrite.

- Added an ApertureBase superclass to help reduce redundant code.
- I looked at astropy.photutils and found many similarities (namely, aperture
  classes that carry extent and pixel weight information). I've therefore taken
  some inspiration from their overall design, e.g., performing photometry in a
  function that takes a set of apertures rather than having the aperture
  classes keep track of the image data and doing the photometry in a method.
  Implementation details are still my own, however.
More extensive rewriting... almost to something useable
Package!
Created .gitignore
Fixed some importing bugs
Updated script for compatibility with galaxyphot
Removed test/scratch file
Minor bug fix
Finished #2 and #3
Accompanying figures
Merge branch 'test-jake'