Add class option to specify custom classes

[Martin-Nyaga]

Add a class option, to be able to specify custom classes on the toast for more advanced styling than just text and bg colors.

See the demo in index.html.

$.toast({
    heading: 'Custom Classes',
    text: 'Custom classes are specified using the `class` option.',
    class: 'my-custom-class'
})

[bhalial]

I'd like this functionality too, hopefully it gets added :) @kamranahmedse

[kamranahmedse]

Thanks