Remove "Stay logged in" checkbox

Pretty useless, and I can't really see a use for it. It does make that
login form look a bit empty, but I'm sure I'll get used to it.

Closes #193.
Remove references to forgot password page

Lazy workaround so that I don't have to actually make a forgot password
page, which will probably be used all of two times (if that).

Closes #190.