CHANGELOG and AUTHORS and .mailmap updates for 1.9.1

Change-Id: I34b28ffd7971a99b727c5149bdddeb9c6020e1df
version bump to reflect current dev target

Change-Id: I5db26319ba642c6447527f50c7316b8b5933871d
Merge "CHANGELOG and AUTHORS and .mailmap updates for 1.9.1"
Merge "version bump to reflect current dev target"