Allow search by cost object

[adehnert]

The signatories page displays cost objects since ticket #113 / commit d0f076fd668444c1929396ee302f6485bbfa088f, but it might be nice if the search interface supported directly searching by cost object.

(This probably doesn't want to happen until we can either publicly display cost objects, or we can ACL who can use this part of the search UI, though.)

(Suggested by Colin Codner (via zephyr from Quentin).)

[adehnert]

Fixed in commit 7b00af896e2166a8d5a421b3e0f6077613eee4b0

Author: Alex Dehnert <adehnert@mit.edu>
Date:   Thu Mar 14 04:55:16 2013 -0400

    Allow search by account number, officer list
    
    Both had privacy concerns, but I think they're fine:
    
    Account numbers (ASA-#122) can already be looked up, entirely unauthenticated,
    with the account lookup tool (https://asa.mit.edu/groups/account_lookup/).
    Exposing a search for exact account numbers on the search page too seems
    acceptable in this light.
    
    Officer lists (ASA-#123) are mostly public --- they're available to anybody
    with certs, they're on most groups' websites, and I believe we'd display them
    obfuscated to the whole world if we had obfuscation code. The possibility of
    somebody scraping the search page with progressively more refined search terms
    to get this data seems acceptable.