Logger: a native implementation of a logger

Logger allows instanced contextual loggers, and the ability to attach
additional handlers to individual loggers and all loggers.
Class: changing mixin() to use property descriptors

Instead of forcing a property descriptor ourselves, copy it wholesale by
getting it from the original mixin.

This allows mixin in getters and setters.
trait/log: logger trait

Provides `.log` instance, which is an instance of nbd/Logger
Adding Logger tests
Updated test styles and jshint
Adding displayName properties to MVC classes

This is to add the ability to mixin the log trait
0.4.3
Merge pull request #69 from Aintaer/logger

Logger implementation