Move khanload app to contentload.
Clean up some Khanspecific code.
Cleans up contentload to refactor content import into content channels.
Adds basic wrapping for content import.
Adds custom channel importing from a directory structure.
Adds first pass custom channel rendering.
Adds format field to content import.
Allows all content types at any level of the topic tree on sidebar navigation.
Adds test for content importing topic tree generation.
Adds code to reduce bloat in topic_tree denormed data.
Updates khan channel data generation.
Forces knowledgemap generation before topictree stripping.
Updates khan channel data.
Adds documentation for contentload variables and functions.
Cleans up code for contentload.
Merge pull request #2437 from rtibbles/content_load

Arbitrary Content importing from a directory structure