Added an option for changing password.

 - Added a button to the analytics web page that directs
   the user to a password change page.
 - Added a password change web page where the user may
   enter a new password. The new password must be enetered
   twice to prevent user error.
Resolved password change-related bugs.

 - The password is now updated in the sync-account table
   using the serial key for the account. The serial key is
   retrieved from the cookie.