Embedded discussion component defaults to "Discussion"
Blank HTML page defaults to "Text"
Video component defaults to "Video"

These default names show up in tooltips.

Moved to xlint rather than setting to old default.

Warn user that the course behavior may change.

This just wraps XModule.get_html, and ignores javascript and css for
now.

[LMS-189]

add new test to assert that course creation will populate default tabs as expected. Also update factory to not override defaults on tabs array. Also simplfy self.tab test condition.

It seems like self.tabs is getting set to an empty set [] now rather than None. This causes the tab defaulting to not populate, leading to crashes in the LMS if someone makes a new course with additional tabs (e.g. static tabs or pdf-textbooks)

N.B. When we are in a world of mixed XModules and XBlocks, the
system/runtime will have to be cognizant of that when asked to return a
XModule from an XModuleDescriptor child

[#LMS-190]

change from_xml class method on video class to make sure we honor the fact that the xml string could actually be a pointer to another file on disk which actually contains the attributes

A new modulestore backed by mongo that changes the data format to
facilitate easy versioning, sharing content between courses, and fast
lookup of course structure and Scope.settings data.

Conflicts:
	cms/djangoapps/contentstore/tests/test_contentstore.py

https://edx-wiki.atlassian.net/browse/STUD-428

Embed a chat widget (much like the calculator widget) into the
courseware. To use, you must point it at an ejabberd box,
configured as `JABBER_DOMAIN` in the settings.

Update existing tests and provide new ones to test new paradigm.

Refactor new set_many and update XBlock version number.

fix test to use the new create_item method rather than clone_item, which has been deprecated, and thus breaking the test

add a default XML serialization if the 'data' field is empty or None. Some XModules now - like video XModule - do not have XML set in the 'data' field