To do: Wrap hardcorr to find prior for rotation period

[annajungbluth]

It would be nice to include an option to run ACF using hardcorr to estimate a prior for the rotation period. Running ACF should only take about a minute for one light curve.

@annajungbluth can work on this

[bmorris3]

This could be done by creating a submodule (a .py file within the dot/ package directory, hopefully called something like "acf.py" We should stress-test this function pretty carefully to make sure that the initial guess for the period is a good one, since the quality of fits is critically dependent on a good period.

[annajungbluth]

I added a basic function to io.py on the gcp branch. I agree that we need to stress test this a little more though. I double checked the ACF results I got when running the run file with those we had determined earlier. They disagree a little bit, I am guessing this is coming from the level of pre-processing / the lack of pre-processing that we do with the light curves.