Merge pull request #1144 from dachary/wip-7146

osd crush rule create-erasure

gitbuilder is green/yellow for wip-7146

Reviewed-By: Christophe Courtaut <christophe.courtaut@gmail.com>
mon: check cluster features before rule create-erasure

Signed-off-by: Loic Dachary <loic@dachary.org>