A way to share fits

[youngsm]

I'd like to make a standardized way of storing and sharing grblc fits when I get some free time. At a higher level, this will be done by:

• Creating a new serializable Python object, grblc.lightcurve.FittedLightcurve, which contains (1) LC data, (2) fit data, (3) model data,and (3) plotting functionality.
• Create a system of pickling, saving, and reopening these files.