JBAS-1132 Self-reg clear values on page load

JBAS-1132 Self-reg clear values on page load

Clear all text form values on page load to prevent browser-back from
leaking sensitive information.

Avoid unchecking checkboxes on self-register page load to that billing
address == mailing address can be set by default.

Note, page is SSL and caching is disabled.  This was not enough to
prevent the browser (Chrome, anyway) from caching the form values...

Signed-off-by: Bill Erickson <berickxx@gmail.com>