delete_item should update the parent's list of children to reflect the delete operation. Also added unit test

Tag tests not working under PhantomJS to skip for now.

make export a bit more resilient. If there's a piece of metadata that we can't serialize - i.e. someone wrote a new bool attribute and didn't put it in the type mapping table - then we log the exception and continue.

Advanced modules must now be specified individually in order to enable them on the 'advanced' component menu.

of the tests fail.  Deleted some tests.

don't make caller responsible.

but fetch async via json get.

definition not being updated when using defaults. Not sure why this
passed before.

do the metadata comparison on the parent not the course as we don't actually know which vertical we ended up picking (could be arbitrary).

remove unused import commands (which were used for temporary profiling). Also change get_lms_link_for_item() to preserve the previous argument ordering. Apparently all callers may not use argument name conventions for the 'preview' argument.