Additional API methods for notification

[VizuaaLOG]

Over the next few versions I think it would great to expand the API methods available, allowing certain settings to be changed at run time, rather than needing to recreate the component. The below are ideas for the notification, any other ideas please just comment!

• hide() - Hides the notification
• show() - Shows the notification
• toggle() - Toggles the visibility of the notification
• type(new_type: string) - Changes the notification's type, adjusting the CSS classes applied
• body(new_body: string) - Changes the body of the notification
• isVisible(): boolean - Returns true if the notification is visible, false otherwise
• dismissable(new_state: boolean) - Sets if the message is dismissable, returns the current value if no parameters are provided
• dismissInterval(new_value: number) - Sets the message's dismiss interval, returns the current value if no parameters are provided
• destroyOnDismiss(new_state: boolean) - Sets if the message is destroyed when dismissed, returns the current value if no parameters are provided
• size(new_value: string) - Sets the size of the message, returns the current value if no parameters are provided
• trigger(event_name: string) - This will trigger the provided event on the notification instance. Note: This wouldn't be restricted to documented events, so could be used for handling custom events

The current color property will be renamed to type to keep in line with the class names. is-primary is a type not a color.