Abstract logging inmethod RunWithClientAndLogger in plan.go

#### Feature Description

When using the method RunWithClientAndLogger in plan.go:56 we have to provide a pointer to consul api client and a pointer to std logger. The method itself uses just the Printf method of the logger.
Every application uses it's own logging package so we have to provide a "bridged" std logger in order to get a consistent logging experience.

Two possible solutions:

- We could just use a `Printf(format string, v ...interface{})` function in order to avoid instantiating the std logger and allow the user of the package to implement that function.
- Since go lacks of a logging abstraction based on interfaces consul could introduce one and let the user of the package implement it.

#### Use Case(s)

Any relevant use-cases that you see.

Start with RunWithClientAndLogger in plan.go:56 and inspect how it uses the standard logger's Printf method. Review the two proposed approaches and determine the intended logging abstraction; done should provide callers a way to use their own logging package without a bridged standard logger.

Written by the indexing model from the issue text.