was getting unicode errors when exporting CB22x
export_to_xml() really should be definition_to_xml() since we'll rely on the base method that is in xml_module.py to preserve the correct export filesystem hierarchy.
remove commented out line
update tests to call definition_to_xml rather than export_to_xml, which presumes writing to a filesystem, plus it adds a url_name to the attribute set. Also, on __init__ reset the 'category' attribute, on some code paths this can get lost. Not sure why, but this gets all the tests to pass.
Make our deserializing consistent with serializing.

Also fixes problems with double-quoted strings (historical artifact).

STUD-640

Conflicts:

	common/lib/xmodule/xmodule/video_module.py
Add test for invalid YouTube IDs strings
have XModuleDescriptor properly ensure category is set
use same getattr pattern in the XModule constructor that exists in the XModuleDescriptor
Correctly seek in captions with non-1.0 speeds.
Added back old method of getting caption position for Flash video playback.

Because with speed changing the time also changes for Flash playback,
a different way to calculate the current time is needed than for HTML5
playback. I have added conditions for Flash and HTML5 video, and put
old method of calculating time for Flash.

I have tested it on the YouTube video ZwkTiUPN0mg. Both HTML5 mode and
Flash mode have proper video-captions syncing with this fix. NOTE: to view
YouTube video in Flash mode you either have to use an old browser (ex. Firefox
version 18) or hard code in source that state.currentPlayerMode = 'flash' (in
function _setPlayerMode(), file 01_initialize.js).
in grading, if problem cannot be created, return score as none

Conflicts:
	lms/envs/dev.py
Merge pull request #714 from edx/zoldak/hotfix-2013-08-16

Zoldak/hotfix 2013 08 16