style(*): add doc strings to deisctl and logger

This change quiets most `golint` warnings for the *deisctl/* and *logger/* components by adding go doc strings. It also removes several functions in the `deisctl/utils` package that were unused.

I would appreciate feedback on the accuracy and usefulness of the doc strings in particular.
> What exactly is a configuration value? How do we store them and how does the cluster interact with it?

I don't know. What would you write here? Whoever wrote the code should have documented it in the first place, I'm just trying to fix their mess.