Consolr updates

[defect]

In order to support more tools than ipmitool in consolr, I'd like to modularize it a bit. As you can see here, I've moved all the ipmitool-related code in to a class called Consolr::Runners::Ipmitool. The command loads one or more runners dynamically from the config, and chooses the first one that reports it can run on a given node (meaning the runner's can_run? method returns true).

An example use case could be an environment with mixed Openstack VMs and bare metal servers. An openstack runner would then handle all the VM assets and the ipmitool runner all the bare metal assets. This way, you can easily customize consolr to new tools by writing a Consolr::Runners::Yourtool class and then installing it in whichever way you prefer.

In order to maintain backwards compatibility I've made the ipmitool runner the default if no runners are specified in the config.

Finally, I'm adding an option (-S, or --status) which just returns the power status of the assets because it seemed like something that would be useful :)

@tumblr/collins

[byxorna]

LGTM

[roymarantz]

[picky] whitespace

[roymarantz]

IMO there should be some way to force using a particular runner.
Do you want to add missing ipmitool functions in the PR (e.g. soft reboot vs hard reboot) or is that too much out of scope.
I like the approach though.

[gtorre]

Very nice. 👍

[defect]

Added support for --soft-reboot and --soft-off. I also added a --runner option to specify a specific runner to use.

[william-richard]

This LGTM
But, I think we should add a barebones example gem that would show people how to add their own, internal runners with custom logic.

[william-richard]

Can you also add unit tests before merging?