Multiple bug fixes

【Contents of the fix】
■Fixed a display bug on the password protection page when “Content leading to membership registration” is not selected.
■SSL support for “Google Custom Search” widget.
■Fixed minor bugs.

The following files have been modified for this update.

【Modified file】
functions/password_form.php
functions/update_notifier.php
languages/ja.mo
languages/ja.po
style.css
widget/google_search.php