Draft: move logging and alert follow-up into threads

Speed up sending HttpResponse's back to users by moving follow-up actions (like creating new logs and issuing kafka/phone/email alerts) into a non-blocking thread. The actions to modify are listed below:

Superevent actions:

• Create new superevent
• Add event to superevent
• Add superevent label
• Remove superevent label
• Create new log message (includes file upload)
• Remove event from superevent

Event actions:

• Create new event
• Add event label
• Remove event label
• Create new log message (includes file upload)