[r=wallyworld] Migrate manual provisioning to API
Manual provisioning now works using the API.
Two new client endpoints are provided:
InjectMachines
MachineConfig
The MachineConfig API is similar to the ContainerConfig
used by the local provider, however more information
is required in order to handle provisioning bootstrap
as well as normal host nodes.
Some refactoring of the ProvisionManchine method was also
done to split it into smaller chunks.
https://codereview.appspot.com/23440043/