Add notification style options

Add the style options to the notification constructor and to the notification default options $.notificationOptions, you can set the background color, color and opacity of the notification by setting style property like this: 	

<code>$.createNotification({content:"Hola mundo!", "style: {color: "#000",backgroundColor : "#fc5a17",opacity : 0.8}}); </code>

The notification default style is <code>style: {color: "#fff",backgroundColor : "#000",opacity : 0.8}</code>