model_2MASS_vega_ab.py verifies 2MASS AB transformation

FSPS pretty much agrees with Blanton. That's great!
Model PHAT ACS/WFC3 -> ugriJK with FSPS

Wrote scripts to syntheize SSP magnitudes in HST and SDSS or 2MASS
bandpasses and fit a forward transformation from HST to ANDROIDS.

- Use FSPS to fit WF3/IR to JKs transformation
- Model u-band from WFC3/UV PHAT photometry
- Model PHAT/ACS to gri
Implement HST/PHAT transformation functions to ugriJK based on FSPS scripts

The fit coefficients are manually transposed from the output of the
scripts.