Add password changing

[gaimerI]

Adds a way to change password.

Note: this first deletes the account, and then makes a new one with the same username and the new password. There's definitely room for improvement here, but I'm not sure if the server side is ready for anything more complicated.

UPDATE: Changed stuff - should work better (idk what I did)

Positive:

• changes password
• should do it no matter how many times user does it

Negative:

• nothing