Feature/victor/metadata inherit

Conflicts:
	lms/templates/discussion/_forum.html
	lms/templates/discussion/_inline.html

* problem was on import to json--got all the metadata,
  but didn't preserve the _inherited_metadata
* added own_metadata property, use it instead

* also make a placeholder roundtrip export test

* make logging work properly in cms, dev
* fix a comment

Strip down sequence nav, start to use ems for font size instead of pixels and started to strip down the info page

Added more styles for the info page and added headers for the updates and handouts so they will be consistant for every class

Jarv/prod requirements

add back-compat code to customtag

* apparently 6002x is using the impl-as-child structure already.

Feature/victor/xml verify