document create_pool erasure_code_profile_name argument

Signed-off-by: Loic Dachary <loic@dachary.org>
fix create_pool_with_unique_name call to use profile name

The hardcoded arguments are deprecated for the profile name. Create a
profile that matches the previous default arguments. Read the config to
allow the caller to override the defaults from the yaml file.

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #281 from dachary/wip-lost-unfound

fix create_pool_with_unique_name call to use profile name

Reviewed-by: Sage Weil <sage@redhat.com>