Added fix for Issue#977
changed line to if PY3
Change to common argument order in AngularSeparation
add test for AngularSeparation behavior
add exception module to utils
added warning for swaping lat/lon in AngularSeparation initializer
Added backwards incompatible changes section to What's New
Changed units-checking to work on real first argument
Consistent lon, lat for AngularSeparation

In the recent renaming a bug was introduced for a special case
(degree to radian conversion wasn't done).
This is now fixed and covered by a few more unit test inputs.
Fixed "shortcut" for when only leading parameter of AngularSeparation is non-0
Support letting the second, third, and fourth args of AngularSeparation be None
Merge pull request #3 from eteq/cdeil-angsep-fixinit

fix for AngularSeparation initializer oddities
made the encode fix at line 861
Initial import of models
Add models documentstion
Put documentation in astropy's templates
Update docs/models/index.rst
Update docs/models/index.rst
Update docs/models/fitting.rst
Update docs/models/models.rst