Merge branch 'release/0.9.2'

* release/0.9.2:
  Bumped version number and wrote release notes for 0.9.2 in preparation for release.
  Fixed an exception with JSONAttributes using DateField or DateTimeField as their field template when the stored value is None. Fixes #178.
  Updated copyright date range to end in 2012 instead of 2011.
  Added include_package_data option to setup.py to ensure MANIFEST.in is actually heeded.