R1:02fb5fea89e6

Allow configuration of a minimum password length, unify password reset
interfaces

Summary:
- We have a hard-coded minimum length of 3 right now (and 1 in the other
interface), which is sort of silly.
- Provide a more reasonable default, and allow it to be configured.
- We have two password reset interfaces, one of which no longer actually
requires you to verify you own the account. This is more than a bit derp.
- Merge the interfaces into one, using either an email token or the account's
current…