Allow bulk editing of Admin Flags in Attendee admin

[naokomc]

Currently, there is no easy way to enable admin flags in bulk from the Atendee list screen in the dashboard.

My workflow is usually this:

1. Search for coupon code or answer or a question using the "Search Attendees" box.
2. Hit "Enable" link of a relevant admin flag multiple times until I get to the end of the list.

This manual process is time-consuming especially for a large event and prone to mistakes. I'd love to see some kind of bulk editing option. (Better yet, auto flag based on the search in the future)