Move from inheritance HTTPClient in Ironic client

In the process of unification of the clients code we should use
composition to allow easier replacement with common HTTPClient.

Related to blueprint common-client-library-2

Change-Id: I9450c4d53f85e0dfabf9b1c49e001338d73b83f6
Enable rebooting in the client lib and cli

The client library should be able to request that a node be rebooted by
passing the "reboot" state to the API. This functionality should be
exposed in the CLI as well.

This depends on commit Ic13c046c621211d9c1533325812955233441d2da

Change-Id: I7954c02a3b5fd8f6caa574fd581f2ae3b0c3d422
Merge "Enable rebooting in the client lib and cli"
Merge "Move from inheritance HTTPClient in Ironic client"