Refactor get_parent_locations STUD-1663

LMS-1724

update course info module to save content in new 'items' field + update import/export to handle content field other than 'data' or 'metadata'
STUD-154

with code to translate between addressing schemes based on app
and persistence layer addressing scheme specification.

STUD-1206

html page and update access use 2 different urls
GET update can get an individual update
STUD-944

Fixes bug STUD-590.

Instead, we use XModule field default values when creating an empty
XModule. Driven by this use case, we also allow for XModules to be
created in memory without being persisted to the database at all. This
necessitates a change to the Modulestore api, replacing clone_item with
create_draft and save_xmodule.

returning the content in same form as it was saved rather than parroting
it back.

show an alert.

Addressed some of Christina's review comments.

other course info bugs (not editing/deleting right element if > 10,
putting new elements at end rather than beginning of list).
Made Location more robust against parsing errors.