Moved discussion XBlock to edx-platform
(cherry picked from commit a7c0a2a)
Copied test specs
Add topic selection to inline thread editing, fixing errors

Co-Authored-By: Brian Talbot <btalbot@edx.org>

TNL-549

Conflicts:
	common/static/coffee/spec/discussion/view/discussion_thread_edit_view_spec.js
	common/static/coffee/src/discussion/discussion_module_view.coffee
	common/static/coffee/src/discussion/views/discussion_thread_edit_view.js
	lms/djangoapps/django_comment_client/forum/views.py
Backported edx-platform hosted discussion XBlock to edx-solutions (part 2)
Temporary fix for runtime.resources_fs error
Fixed broken bok_choy tests + added API key for bok_choy environment setup
Fixed other broken bok_choy tests: environment setup
Disabled starting discussion course apps (DiscussionApp and DiscussionProfileApp) on DOM ready:
* Added scripts to XModule templates to start the apps..
* Added explicit call in XBlock to start required app.

Added concept of local urls - required to substitute absolute links for user profiles for relative in Apros
Global setting for asynchronous ajax calls - to overcome firefox's strictness about using synchronous ajax with credentials
Merge pull request #295 from open-craft/eugeny/discussion-backport

Backported discussion XBlock to edx-solutions