* add a days_early_for_beta inherited policy option
* students in the beta_testers_{COURSE} group get to see content that many days early
* Clean up some docstrings related to time formats
* Add basic test
This directory contains some high level documentation for the code. We should strive to keep it up-to-date, but don't take it as the absolute truth. A good place to start is 'overview.md'