This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
- All unsubscribes go to the exact same page
- You may unsubscribe from watching a category on that page
- You no longer need to be logged in to unsubscribe from a topic
- Simplified footer on emails
