[Feature] Implement password change

[Jack-Edwards]

Crypter currently allows users, who have a verified email address, to perform account recoveries / password resets in case they lose their password.

Crypter should also allow users to change their password without having to perform an account recovery. This will enable every user to change their password, provided they are logged in and know their current password.

Requirements:

• An authenticated user can change their password.
• The user's current password must be provided in order for the password change request to be completed.
• The user's current master key is re-encrypted using the user's new password.