Despite its documentation the "constructor" of RevisionList tends
to expect array of revision data in a format returned by API instead
of array of Revision objects.
Due to different name of ID fields in Revision object and in API array,
if "real" Revision object is passed to RevisionList, its ID is lost.
This changes RevisionList so that it only accepts an array of Revision
objects. This provides better abstraction.
This is basically a revert of I147270f28381038d05f8bcfd2317e8c269b2e458
which aimed at the same problem but suggested solution doesn't seem right.
Change-Id: Ic45cdd3e7b707a8c6a19eecf0a84d4c11696cd1f
