Add nested option

[Deuteu]

To allow nesting of confirmation modal as requested in #54

[mnapoli]

Great! But is the option necessary? If it works well then why not allow nested confirms? Do you think it could cause issues in terms of user experience sometimes?

[Deuteu]

Oooh, like change default behaviour and always nested if there is all ready a .confirmation-modal opened ?
I didn't think about that (I was driven by the other options I've added so I followed this path) but can be a good thing.
Will see that. (Might not be soon but will let you know asap.)