From @fgimenez suggestion on #3, it would be better if we use constants for the verbosity levels, with iota.

My proposal is to use QUIET, LOW and HIGH.

This is an issue to discuss later.

Federico thinks the interface has a lot of methods and it would be better to define an event and only one add method that receives that event as an argument.

I think that the interface is clearer when the actions are reflected in the name of the methods, instead of defining a generic method that receives a selector argument.

The logger has many of the same problems that the reporter has.
It needs to be defined as an interface, so we can extend it in any form we want.

Then instead of controlling when the output is flushed with the verbosity flags, we can use the verbosity to control how much is printed, and the implementation of the interface to decide when and where it goes.