Cleanup Code!

Major changes I have made:

 * Standardized syntax
 * State-based operation (i.e. RSColorPickerState)

`RSColorPickerState` is a class which represents the current selection of the color view. It makes it easy to change parts of the state while keeping other parts the same (i.e. changing brightness, alpha, or hue+saturation). This unified source of information makes the getters and setters implicit and removes the need for otherwise necessary instance variables.

In the old RSColorPickerView, there were instance variables for alpha, brightness, selection, selectionColor, etc. This information was redundant, and using a universal state object removes this redundancy.