Add sanity to DifferentialRevisionQuery

Summary:
Changed cc/reviewer search to be a union/or instead of intersection/and within
each list. Also added support to search for multiple authors (same behavior as
cc/reviewer), and updated conduit call to match. (See discussion on D1158.)

Test Plan:
Used the conduit call to search for revisions with one of 2 people on the cc
list, and checked the results to see that it wasn't constraining to requiring
both be on the cc list.

Reviewers: epriestley, jungejason, btrahan

Reviewed By: epriestley

CC: aran, nh, epriestley

Differential Revision: 1179