Make detach action idempotent

- Made the detach action idempotent by not raising an error when no
  volume exists.
Pass in the parent_volume_snapshot_href correctly for creating volume snapshot.
Set IOPS in volume create API call if provided.
Fix the logic in skipping volume deletion error

- The volume deletion in OpenStack also gives an error if there are
  any dependent snapshots but with a different error message
  compared to Rackspace Open Cloud.
- Also the RightApi::Exceptions namespace is not included by default
  when requiring 'right_api_client' and this namespace is also
  deprecated so use RightApi::ApiError instead for rescuing exception.
Make nickname the name parameter.
Don't use idenity_attr and use name_attribute instead
Set name as the identity_attr.
Don't use identity_attr or name_attribute.
Fix up more changes.
Remove delayed_evaluator dependency

We had this cookbook because Chef 10 didn't have support for lazy. Now that we are on Chef 11, we don't need this dependency.
Do not include delayed_evaluator.
Skip volume deletion check in rackspace-ng and openstack.
Remove parentheses for consistency.
Merge pull request #7 from rightscale-cookbooks/white_14_04_acu114920_make_detach_idempotent

White 14 04 acu114920 make detach idempotent