Add include/exclude filters for pod names

[dansimone]

This PR adds parameters that allow pod to be filtered in/out by pod name. This is a useful feature because some existing Kubernetes applications (the one I work on is an example) don't have the necessary labels that are required to make use of the existing chaoskube label selector filtering. So for those users, this just allows them to provide a simple regex pattern for pod names to include and to exclude.

Also includes:

• README updates to indicate the new usage
• Necessary test updates, including verifying the new capability in TestCandidates().

[dansimone]

@linki let me know what you think about this.

[linki]

Hi @dansimone,

thanks a lot for your PR and sorry for the late response (I was travelling).

Looks pretty good to me, I'm happy to merge.
I just added a couple of minor remarks. Let me know what you think about them.

[linki]

Thanks @dansimone 🎉

[dansimone]

Thanks @linki, just circling back to this now. Your comments sound great, and thanks for making those changes!