Prefer simplejson to json, when available
Merge pull request #5 from edx/simplejson

Prefer simplejson to json, when available
Not sure how this slipped through, but widgets are now called Fragments.
Merge branch 'master' of github.com:edx/XBlock
We don't need this sequence numbers on fields.
Fix the code so that student_id is always a string.
implement object identity, and first round of tests
Now it's possible to request specific views from the workbench URL.
provide caching for object identity
Tweak docstrings.
XBlock.load_tagged_classes will give you classes with particular tags.
Add a test of a handler, refactor how scenarios work to simplify tests.
Add selenium LiveTestServer tests for thumbs
Fix case in comments.
Merge pull request #8 from edx/feature/brian/object-identity

Feature/brian/object identity
Maybe the final change to how student_id is handled so it work properly?
Update README with info on testing.
Add display_name to Fields.
Add example of display_name being set.
Merge pull request #11 from edx/feature/christina/display_name

Add display_name to Fields.