added font inside a new scss file instead of link tag from the index.html
fixed RefuelModel.getTotalKilometers when using multiple cars
changed this by RefuelModel in all the static methods for the RefuelModel, just for clarification
changed this by CarModel in all the static methods for the CarModel
added instance methods and static methods comments to CarModel
improvements regarding time functions, we are using a TIME constant now, and only one function that converts the unit time inside instead of using multiple functions
replaced car.make + ' ' + car.model by the new magic car.getName function, thanks @pablosca
multiple car stats, filter by car with a dropdown closes #59
some stats added mentioned in issue #19