Drop indexes from the Index Page

Eben has a change which makes a Drop and Edit button appear on each index on the Global Index page. http://review.couchbase.org/#/c/89825/ 

Currently they take the user to the Query Workbench with a statement ready for the specified action. The Drop button should issue that query in-place without taking the user away from the index page.

We are not trying to handle all the conditions/events/warnings which could happen after the button is pressed. Probably should just disable the button after pressing and let the index disappear on the next page refresh.