Use # instead of """ for copyright blocks

Reformats copyright messages to be comments rather than
docstring-style blocks.

Change-Id: I4d863f53b67bb49d03bda0952b9e6179b6d23c59
Merge "Use # instead of """ for copyright blocks"
Resolve circular import, introduce ExecuteCommandMixin

Adding new methods to utils won't work as the circular import appears
between errors.py and utils.py.

Introduce ExecuteCommandMixin and use it for IronicPythonAgent and
FlowExtension (in future patch).

Also add tests for its.

Change-Id: Id95b31349292a7967d2ee66ec82c1662d8e5de94
Add self to validator method

This patchset allows access to extension class instance for more
advanced command validation.

Change-Id: I9d6df1ab44ab06ef2e663ad777ad3560d9ab7565
Add FlowExtension

It makes possible of running data-driven flow which's the list of
the other existent extensions to be called.

Change-Id: Ib73ea4da92f291c872b7ae51e46ecc7fdd45ee16
Kill the build_agent function

This used to actually do things, now it just wraps the constructor.
Lets kill it.

Change-Id: I320684f8f52d032a1755460eacc70f5aeee92d7a
Merge "Kill the build_agent function"
Merge "Add FlowExtension"
Use configurable driver name in lookup URL

Allow configuration via command line arguments or kernel parameters.
Default to agent_ipmitool, the reference driver.

Depends on https://review.openstack.org/#/c/84795/12

Change-Id: I55c4a8713308d038002a6567471cd862bf89ec76
Merge "Use configurable driver name in lookup URL"
Minor fixes to image build

- Correct directory to match the relative path correctly
- Include additional requirements.txt for coreos image injector

Change-Id: Ie68f86220f2db786e3e97e72fed288b92704d028