Updates to match client and server model properties

Also changed "save"s to "set"s to prevent changes from being written to
the server.
Changed the filter array to a collection with a filter model to match
the server model.
Fractal preview

Added dummy preview image to the fractal model.
Added code to display the preview image and to clear it when the
fractal inputs are changed.
Added python method to create preview images.  These can be smaller
than the fractal and are in black and white.
Add backbone-tastypie.js
Override save() in RawFractal model

Now, when a RawFractal is saved, a matrix file and a preview file
are generated from size, roughness and perturbance. The files are
uploaded to the rawFractFile and rawFractImg fields.
Backbone-tastypie.js everywhere.
Ignore docs.
Set up api

Currently, POST from backbone fails with 404.
Make fractalgen.calc a python module.