API commands

* add low-level API discovery support

Change-Id: I7c4187cbe00525677d824422b542cbc2c349e6e6
test work

Change-Id: I0b2fd9d2a0103b42ec7cc4ed98d5bcfdec27c6fe
Merge branch 'discovery' into dt-test
Merge branch 'oslo-clean' into dt-test
Merge branch 'image-v2-v2' into dt-test
Merge branch 'identity-ec2-tests' into dt-test