Add @profiler.trace_cls decorator

* This decorator allows us to add @trace to all public (and optionally
private) methods of class.

Sample of usage

> @profiler.trace_cls("rpc", info={"any": "info"}, hide_args=False, trace_private=False)
> class SomeClass(object):
>
>     def traced_method(self, arg1, arg2):
>         pass
>
>     def _non_traced_method(self, some_arg)
>         pass

* Improved @profiler.trace decorator
  Now it set's full path path including class name of method.

* Use separated scope for method's: name, args, kwargs.
  make it much easier to read trace info

* Update read me

Change-Id: I45b0dd7c2acdfc5bf66470bd4d15872a3a379af5