Provide more customization

[nirvana-msu]

It would be great if there was more flexibility to customize toasts out of the box. Specifcally, the following would be very welcome:

• Specify (optional) id for the toast div
• Specify (optional) classes for the toast div
• Add an option to prevent adding dismiss button (e.g. for when toasts should instead be dismissed programmatically based on some kind of interaction with the toast)
• Have create return html element, allowing the user to customize it further

Thanks!