Update doc/README.md

proposed comment about how to use PostGIS 2.0. Currently receiving an error regarding compatibility between django and PostGIS 2.0 "The error was: operator class "gist_geometry_ops" does not exist for access method "gist""
Merge pull request #1 from djq/patch-1

Update doc/README.md with note about PostGIS 2
Update README.md
Add docstring for action list
Merge branch 'master' into apiv2
Update Travis config to cover apiv1, apiv2, and to test any branches