Add generic entity.delete()
Add generic entity.delete()

Change-Id: I00188326b6343a4eb4d1dd1b6a24e691ffd30415

ntt-sic/python-keystoneclient,ging/python-keystoneclient,alexpilotti/python-keystoneclient,sdpp/python-keystoneclient,metacloud/python-keystoneclient,Mercador/python-keystoneclient,darren-wang/ksc,sdpp/python-keystoneclient,ging/python-keystoneclient,citrix-openstack-build/python-keystoneclient,klmitch/python-keystoneclient,citrix-openstack-build/python-keystoneclient,Mercador/python-keystoneclient,jamielennox/python-keystoneclient,magic0704/python-keystoneclient,darren-wang/ksc,jamielennox/python-keystoneclient,jamielennox/python-keystoneclient,ntt-sic/python-keystoneclient,alexpilotti/python-keystoneclient,citrix-openstack-build/python-keystoneclient,metacloud/python-keystoneclient,magic0704/python-keystoneclient,klmitch/python-keystoneclient,ntt-sic/python-keystoneclient