Code to produce descDithers.

[humnaawan]

As @rbiswas4 requested, the code here produces csv files with descDithers for all the OpSim outputs included the cadence optimization call. Also, there's some guidance on how to use MAF Stackers to add dithered pointing columns. Addresses #3.

The readme has further details.

[humnaawan]

@MichelleLochner I am sorry but I am going to make some further changes to the code for a few more updates:

• Make code runnable by anyone. This'd require the updated rotational dither stacker to be approved or be made available in some other way; I am working with @rhiannonlynne to figure this out.
• Make the code runnable with minimal interaction, i.e. save relevant plots without having to run it in the ipython notebook.
• Add a readme to keep track of the files in the output directory, alongside tracking the sims_maf verison used.