Update __repr__ method to display more information.

Update docstrings.
Handle explicit and implicit distribution point configuration, and JDS.

For "old-style" DP declarations, use existing method of using
distributionpoints results to populate connection arguments.

For "new-style" DP declarations, pull information from the
JSS.repo_prefs property.

Add helper methods for adding/removing DP's from DistributionPoints.

Add JDS DP's to DistributionPoints.
Update CHANGELOG.