Change from AGPL to Apache 2.0
Merge pull request #231 from edx/ned/liberal-license

Change from AGPL to Apache 2.0
Ugh, not this repo.

This reverts commit bfa090dbbe90664451df1a032e9864f17d27f7fd, reversing
changes made to a4c84afcc445624d05b076ff016d5448c07bc80c.
change the field
DateTime allows incoming value to already be a datetime
Merge pull request #233 from edx/dhm/datetime_native

DateTime allows incoming value to already be a datetime
Allow a json_handler to return a Response object
Merge pull request #235 from singingwolfboy/json-handler-can-return-response

Allow a json_handler to return a Response object
Merge pull request #234 from edx/danielli/pyfs

We use fields to generate keys. This fix makes this work in edx-platform, where these are not strings. 

By abstraction, we should generally not rely on this being "stringy," but in this case, we went through this with Cale, and it seems like the least of all evils. Otherwise, we'd replicate a lot of code.
Correct declaration for scope_key.
Merge pull request #237 from edx/pmitros/fix-scope-key-encoding

Correct declaration for scope_key.
Change from AGPL to Apache 2.0
Add missing authors
Call super.__init__ from xblock.__init__
Merge pull request #245 from cpennington/call-super-init

Call super.__init__ from xblock.__init__
Implemented error handling for XBlock instances
Merge pull request #240 from edx/lmorales/xblock-error-handling

Implemented error handling for XBlock instances
Extract Field machinery out of XBlock into 2 mixins

[PLAT-207]
Fix up some pylint complainery
Merge pull request #251 from cpennington/extract-field-machinery

Extract Field machinery out of XBlock into 2 mixins