Global registrant search for superusers.

commit 049b058adb918f4688bfd3ee5685a21eba43913e
Author: John Eddie Ayson <je@bixly.com>
Date:   Sat Jan 19 17:24:27 2013 +0800

    changed user_id field to text input

commit 73d71bd7ad3f8656cf32318068c10726b2b12a2d
Author: John Eddie Ayson <je@bixly.com>
Date:   Wed Jan 16 08:41:40 2013 +0800

    added global event registrants search view
Merge branch 'master' of github.com:tendenci/tendenci
Making first name, last name, and email search case-insensitive.
If the registrant has a user account.  We link to it.
Merge branch 'master' of github.com:tendenci/tendenci