auto unsubscribe users if monitor term is replaced by new term and other automation

[zllovesuki]

currently notification API does not account for term code, there should be a worker to auto unsubscribe after deadline has passed, and dynamically updates the workers to fetch the newest term.

Milestones:

• [x] [UCSC Course Data Fetcher] Upload persistence data to S3
• [X] [UCSC Course Data Fetcher] Poll and compare terms list between S3 and pisa
• [X] [UCSC Course Data Fetcher] Automatically download newest terms and coures (+index and frequency)
• [X] [UCSC Course Data Fetcher] Periodic Refresh of RateMyProfessors data
• [X] [UCSC Course Watcher] Poll and compare latest terms on S3
• [X] [UCSC Course Watcher] Switch to monitor new term when available
• [X] [UCSC Course Watcher] Stop monitoring 21 days after class start (that's the drop deadline, usually)
• [X] [db2Queue in Notification] Automatically switch to new term to be monitored
• [X] [Notification] Poll and compare terms list between local and S3
• [X] [Notification] Switch to monitor new term when available
• [X] [Notification] Automatically unsubscribe users 21 days after class start (drop deadline, usually)

Caveat: automatica unsub is done by termId identification, it doesn't actually unsub

[zllovesuki]

Priority! SlugWatch is now official! We must finish the to-do list!

[zllovesuki]

8f88c1f1792ce32e712655a01239f5743fd7c4e9 basically finished the enhancement. closing.