Add container option

[kevguy]

The original adds a <div> with id snackbar-container by default and appends new snackbars to the container. Though we also have an id option to configure where we want to add a new snackbar, their behaviors are different that the ones in the snackbar-container since some of the code like click handlers are hardcoded for #snackbar-containers only. I think more can be done by letting user set where they want to add the new snackbars but still have the same behaviors like the default container.

An example usage is this:

var options =  {
    container: "new-container",
    content: "message for snackbar", // text of the snackbar
    //style: "toast", // add a custom class to your snackbar      
    onClose: function(){ // callback called when the snackbar gets closed.
        console.log('closing');
    },
    timeout: 5000 // time in milliseconds after the snackbar autohides, 0 is disabled,
};

$.snackbar(options);