Update to current implementation of API.

* Update HTTP client to match existing API implementation
* Add extra fields to flavors test
* Fix server booting and related operations
* Add keypair authorization for ssh and helper functions
* Tidy up server actions
* Move to keypair auth instead of password auth
Merge dev branch fixes

Change-Id: I87d44cdb19f195181f16d0fdf3b9ba65d04b7a7b