initial commit for the console logger

This is a very basic implementation and is missing scoping altogether. Just wanted to put this out there for some feedback. The colors and format match the NLog configuration in the sample app, as evidenced by the image below. 
![consoleloggerinitial](https://cloud.githubusercontent.com/assets/2818455/4500693/3b65c814-4a98-11e4-998b-414ec6c792f6.png)

@Eilon better to have the filter never be null. _filter = filter ??(_, __) => true;