If a scorable block either has a custom completion strategy, or is
marked as excluded from completion, don't record a completion when its
score is updated.
* Vertical marks blocks completed when viewed.
* Functionality is hidden behind a waffle switch
* Submissions from front-end are limited to known-incomplete blocks
* Upgrades xblock to version 1.1.1
* Related future requirements listed in TODO tagged with EDUCATOR-1778
and relevant opencraft OC-* ticket IDs.
OC-3088
* Add a handler to mark a block complete when a problem is scored.
* Also handle marking incomplete when user problem state is deleted.
* Add score_deleted to published providing_args for PROBLEM_{RAW,WEIGHTED}_SCORE_CHANGED
OC-3089
* Submit a completion when receiving a completion event from an XBlock.
* Handle legacy progress events.
* Convert handler to use a dispatch dict instead of an if-else chain.
* Extract masquerade checking from individual handlers.
* Gate submit_completion on waffle switch
* 404 on handler views when trying to submit completion without waffle
switch enabled.
OC-3087
Disallow calling submit_completion when waffle flag is disabled.
Add tests that trying to publish completion errors.
