organizationmap: joe.buck@inktank.com is Inktank

Signed-off-by: Loic Dachary <loic@dachary.org>
mailmap: fix typo in Alexandre Maragone

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #1073 from dachary/wip-mailmap

mailmap updates

Reviewed-by: Sage Weil <sage@inktank.com>