Removed detection of config file, style fixes

The primary change is the former line 50, as it previously functioned it would check for the existance of the config file in the .aws directory and do nothing if present.  I think this is a bit counter-intuitive, as Chef's internal templating system takes care of deltas for us.. If you add more parameters, say multiple aws profiles, the config file does not get updated.  Remove this line, and it does.

I threw in some RuboCop style fixes to boot..  thanks for the great cookbook, really simplifying a project I'm working on!