Allow a user to choose the phpcs version

[mrrsm]

With phpcs 3.0+ rules not being compatible with 2.9 and below rule sets we need a way to tell codeclimate which version it should be running tests with. This is especially important when we are using custom sniffs. I believe some of the other plugins/engines allow selecting versions so it should be doable in a similar fashion I would hope.

[kesselb]

Any updates on this?