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
Revamped system for managing authentication tokens.
- Every user has 1 token per client (web browser)
- Tokens are rotated every 10 minutes
New system migrates the old tokens to "legacy" tokens,
so users still remain logged on.
Also introduces weekly job to expire old auth tokens.
