Edx-proctoring

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* Add management command for updating an attempt status based on its associated review

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* Add testing for exam attempt email failure and related logging
* Fix signal handler connection

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* Get verified name enabled from name affirmation service.

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* Add exception handler and logging to proctored exam attempt emails. This prevents user errors
if the email is not able to be sent.

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* Bug fix for exam registration

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* Re-added code for using a verified name for a proctored exam attempt that had been reverted.
Replaced with signal emitters, which will allow name affirmation to contain the logic for deciding
when a verified name should be created or updated. Also restructured signal files to differentiate
between signal senders and signal receivers.