To the left of each path display a checkbox that indicates if
the file has been marked as reviewed by the user. Toggling the
state of the checkbox updates the reviewed flag for the file.
To acquire the reviewed flags in bulk for a revision the /files/
collection has been modified to accept a "reviewed" query parameter.
Change-Id: I306ba919060b89f162885159e46e20253aad2db2
984747d49f