ceph-manager: fix ec_pool parameters

* the crush ruleset and the pool create parameters must be identicals
  k=2 m= 1
* the --property argument is invalid
* the failure domain is ignored on pool create

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #215 from dachary/wip-ec-pool

ceph-manager: fix ec_pool parameters