add(dep): Added yell to Gemfile

This gives us much more flexibility over the stdlib logger for things
like JSON output and better formatting options
feature(logging): logger now includeable in class

This creates a global configurable logger that can be included in
classes as needed.
update(wrap): Use new Shrinkwrap::Logging module

Update method calls and add include
Merge pull request #2 from philk/set_loglevel

Improved Logging