Fix/cdodge/bad links can cause exception on rewrite

Video Player: minor fixes

Feature/cdodge/add a mixed modulestore

Add a 'MixedModuleStore' which aggregates between XML and Mongo Modulestores

xblock fields persist w/o breaking by scope

Correctly seek in captions with non-1.0 speeds.

Fix for video and captions sync. Test for this fix.

fixed encoding declaration

Enable the django_nose app by default

Conflicts:
	common/lib/xmodule/xmodule/video_module.py

Zoldak/hotfix 2013 08 16

xgettext seems to only like `utf-8` not `utf8` so string extraction
was failing without this

fixed typo in faculty member settings text

This was confusing translators as didn't make sense in English

Conflicts:
	lms/envs/dev.py

Fix initial loading bug on `<formulaequationinput />`

And fix get_explicitly_set to use it and to get the json not native
field values.

It's a reasonable demo of in memory xblock creation, but doesn't fit
the xblock pattern. Moving temporarily to keep the dag persistence test.

and fix some comments ref'g old names

Letting xblocks handle scope rather than separating fields into
different attrs. Although, split still shunts content fields to a
different collection than setting and children fields.

The big difference is that content fields will always be a dict and not
sometimes just a string and there's no special casing of 'data' attr.

The other mind change is no more 'metadata' dict.

in grading, if problem cannot be created, return score as none

add a filter to get_courses to not surface any courses that haven't been mapped, unless the store provider has been labeled as 'default'

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).

Video: disable speed controls for unsupported browsers.