Check for 'page' request var instead of suppressing error when not set.

Prevents PHP Notice on WP admin pages when WP_DEBUG is true.
Add filters & actions to gf_edit_forms only when editing a specific form.

Prevents PHP Notice and reduces load time on Gravity Forms overview page.
Use correct path to enqueue colorbox JS

See http://wordpress.org/support/topic/forms-with-conditional-logic-not-working-with-directory-on-same-page and http://wordpress.org/support/topic/lightbox-not-working-20
Fix JS syntax in Search function
Merge pull request #4 from dbarlett/master

Fix various PHP Notices and JS errors