Put the plugin cache at the module level and add test for correct operation.
Put the plugin cache at the module level and add test for correct operation.
Merge pull request #167 from edx/jorr/promote_plugin_cache_to_module_level

Put the plugin cache at the module level
Run tests on Python 3.3
Use six.text_type instead of unicode
ugettext and ungettext don't exist in Python 3
use six.moves.zip instead of itertools.izip
Do metaclasses with six
Python 3 compatibility fixes with six
Use str.format() instead of % formatting
Make Scope hashable
Handle str/bytes issues with lxml
Remove unused TestUsage class that was tripping up nosetests
Support multiple versions of Django QueryDict interface
Fix unicode test for Django
Update doc to indicate Python 3 compatibility
use six.iteritems instead of dict.iteritems
Use six.exec_ instead of exec
request.body is bytes, not unicode
from __future__ import unicode_literals