Merge pull request #1060 from dachary/wip-mailmap

mailmap updates for reviewed-by

Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: João Eduardo Luís <joao.luis@inktank.com>
Reviewed-by: Noah Watkins <noah.watkins@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Reviewed-by: Yan, Zheng <zheng.z.yan@intel.com>