jsonrpc: StorageDomain_create

Align naming between API.py and schema.

Change-Id: I5f69b7da2098d4f944ee8e9fb16359b67c733261
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/35537
Reviewed-by: Adam Litke <alitke@redhat.com>