Api Exception improvement
Api Exception improvement

ApiException now provides fields with:
* error_code
* error_name
* error_message

Change-Id: I0b8a642eb96835710f62ebf3cca3a5fce071a3fc
Fixes: bug #1282969

citrix-openstack-build/python-saharaclient,citrix-openstack-build/python-saharaclient,citrix-openstack-build/python-saharaclient,openstack/python-saharaclient