mon: test erasure code pool creation

mon: test erasure code pool creation

* The sequence now is a) create ruleset, b) create pool.
* Check that not specifying the ruleset when an erasure coded pool is
  created fails
* Check that specifying a non existent ruleset when a pool is created
  fails
* Check that osd dump shows the expected ruleset. It assumes ruleset
  numbers are allocated in sequence, i.e. the ruleset will be 1.

Reviewed-By: Christophe Courtaut <christophe.courtaut@gmail.com>
Signed-off-by: Loic Dachary <loic@dachary.org>