Password encryption and settings in 4.7

This patch allow the encryption of password in Drupal 4.7 ( using base64_encode and base64_decode appropriatly so that only a somehow plain text representation of the encryption gets stored in the database ) , and converts the hook_user update handler to change the value in a 4.7-ish way.

Another problem in 4.7 was the setting page, which was completly blank. Simply returning the form instead of calling drupal_get_form on it does the trick.

Finally, I've changed the rcmail_page function so that the settings are used.

P.S. : Do note that while bug 67519 exists, editing the form without re-filling the password field leads to it's value being lost. This was already the case before my changes. This can be fixed by either applying the patch I've put in bug 67519 or by switching the password to be shown in an input field ( '#type' => 'password' becomes '#type' => 'textfield' ).