feature roles and permissions

reverting django-user-tasks to 0.1.7 to fix build

JIRA:PROD-553

PROD-533

JIRA:EDUCATOR-4537

* Update Financial Assistance logic

Use the zendesk proxy app instead of the unsupported zendesk library.

* Move to pre-fetching the group IDs.

Rather than making extra requests to zendesk to list all groups and find
a specific group ID. Just make a pre-filled list of group IDs for the
groups we care about.  When a group name is passed in, it is checked
against this list and the ticket is created in the correct group so the
right people can respond to it.

Fix for test that broke related to DRF;

JIRA:EDUCATOR-4541

* Convert to using ExitStack instead of nested.

nested is not available in Python3.

* Use ExitStack from contextlib2.

ExitStack has not been backported to the Python 2.7 standard library and
contextlib.nested is no longer available in Python 3.5.  We need to be
able to use something in both 2 and 3 as we transition so we'll pull in
contextlib2 which has backports of the full python3 contextlib.

EDUCATOR-4554
This fixes a bug where extended due dates were visible in the outline but not reflected on the courseware pages, resulting in problems not being submittable past the due date.
In order for edx-when to work on courseware pages, it has to be more careful about field inheritance, which version 0.2 achieves.

Update the version.

Getting 500 error on stage after upgrading to latest version
of newrelice.

-Removed Submit-feedback View
-Removed related tests
-Removed help_modal.html
-Removed help_modal.html test
-Removed zendesk from requirements
-Updated requirements

added the updated dependency for oauth2

added the commit hash instead of branch

minor fix

changes made by make upgrade