Add metadata for oep-2 compliance.

Allow plugins for the LTI XBlock to pass extra parameters to the provider

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

Add context_title and context_label parameters

Add context_label and context_title to LTI POST parameters; Add required requirements; add some docker devstack instructions;

Additional allowances given to iframe due to the following chrome update from version 64:
https://dev.chromium.org/Home/chromium-security/deprecating-permissions-in-cross-origin-iframes

noraiz/EDUCATOR-1218-fix

make system tolerant of ascii strings with unicode characters

Bump version

Release new version for #31.

Fix the rebind exception when calling get_result

The module used for rebind was set to LtiConsumer instead of the xblock,
which is wrong and causing an silent exception thrown and return 404 to
the client without any indication of the cause.

bump up version

EDUCATOR-121 – Conversion to Django App.

TNL-6688 – Control editing of request username/email fields from studio

https://github.com/pypa/setuptools/issues/964

TNL-6400:no need to translate string coming out of database backend

removed ugettext around display name also

added compiled translations

Add a compatibility function for get_course_lti_endpoints

ziafazal/WL-580: added translation files and transifex config

updated readme

fixed link

better fix for link

Add workaround for Firefox focus issues.

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

Add an OEP-2 compliant openedx.yaml file