mock functionality and tests

[joshspeagle]

Create some functionality to generate mock data from a set of priors. This would draw, e.g., (mini, feh, eep, smf, av, rv, dist, l, b) given the grid corresponding to the MIST models.

• Generating draws from independent priors in parameters should be easy in theory -> (mini, feh, eep, smf) given the utilities I've set up for auto-specifying priors given some labels/grids.
• Generating a draw from rv should be easy given it's a standard Gaussian prior right now.
• Generating a 3-D positions (l, b, d) is slightly more tricky.
• Generating av from a given 3-D position is straightforward.

Once this is done, I should be able to validate performance using one-to-one tests on mocks.

[joshspeagle]

Now that I've gotten to the point where I'm considering, I'm actually not really sure this is necessary. Closing for now.