Update setup.py
Merge pull request #22 from mkelley/enableconfig

Enable configuration at install and module import.
Update README.rst
Merge branch 'ephem-ltt-bug' into v2.0.1
Merge branch 'geom-angles' into v2.0.1
Merge branch 'mkflat-bug' into v2.0.1
Merge branch 'new-quantity-behavior' into v2.0.1
Add observing; version to v2.1
Merge branch 'v2.1.x' into dev
Update to v2.1