This shows the 'problem' icon for LTI units, rather than the default
'other' icon.

AA-75

removed web_fragment deprication warnig

fixed import sequece

updated bleach

Added img to bleach safe tags

Added img to bleach safe tags

Added img to bleach safe tags

added test

added test

added test

added test

added test for attr image

added test for attr image

fixed style bug

Updated format xoe

removed extra formatting

Updated to run tests on both python 2 and 3.

PROD-774

Overview
---------
This pull request makes this XBlock extensible for
adding parameters to the LTI provider in addition
to the existing ones.

Why
---
A customer needs `team` and `cohort` informaiton
to be passed through the LTI channel to simplify
integration with their LTI provider. At the same
time we'd rather not fork the XBlock, so an
Open-Closed model is needed.

More Detailed Documentation
---------------------------
I've added a couple of sections to `README.rst`
to document specifying design and
configuration steps of the new LTI parameter
processors. Please check it out for more
information about the changes that this pull
request introduces.

Example Usage
-------------
I've written a package that we'll need to use for
our customer to pass some personal user
information in addition to the cohort and team
info: https://github.com/appsembler/tahoe-lti/pull/1

Omar Al-Ithawi @ Appsembler

removed ugettext around display name also

This allows this xblock being hooked into get_course_lti_endpoints for
discovering LTI result/outcome endpoints.

asadiqbal08: Updated branch as per suggestions
asadiqbal08: Addressed PR feedback
mattdrayer: Rebased branch, addressed merge conflict

Use django.utils.timezone.now() when determining if the due date of a component has passed to avoid tz-aware/naive datetime comparison bug