LP#1581196: webstaff: fix dirty form detection in patron editor

LP#1581196: webstaff: fix dirty form detection in patron editor

This patch fixes a problem wherein the patron editor
form would think that it had been modified by the
user immediately after initialization.

To test
-------
[1] Load the patron editor, then refresh the page. Note that
    you are warned that there is unsaved input.
[2] As above, but hit the save button. Note that after saving,
    you still get a warning that there is unsaved input.
[3] Apply the page, then repeat tests 1 and 2. This time, you
    shouldn't get inappropriate unsaved data warnings.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>