Correct priorities of HTTP/HTTPS switcher hooks.
Use `env.helpers.url_to` instead of `env.url_to`.
Correct comment in lib/login.js
Move `join_users` hook back to "server:**" channel.
Move `auth_security_policy` global setting to `general` group.
Refactor `general_security_policy` setting.
Use `env.helpers.url_to` to generate email links.