add get_domain function
changes:

- remove the sleep calls for faster test runs
- use Hashie::Mash to make responses uniform
[identity] Add get_domain request
[identity] Add grant_role_to_user_on_domain request
[identity] Add list_user_roles_on_domain request
updated template
Merge branch 'feature/domain' of github.com:devpopol/aviator into feature/domains

Conflicts:
	lib/aviator/openstack/identity/v3/public/get_domain.rb
[identity] Add list_domains request
Add generated cassettes
fix specs
[identity][tests] add grant_role_to_user_on_domain test & cassettes
[identity][tests] add list_user_roles_on_domain test & cassettes
Merge branch 'feature/domains' of github.com:devpopol/aviator into feature/domains
Merge pull request #32 from choodur/feature/domains

Domain related APIs