quick fix for #152: allow users to style dialog types individually

I added the type to the class-name of alertify-dialog-inner. this way, the user can style only one dialog differently: 

    .alertify-dialog-inner-alert {
      background-color: red;
      padding: 25px; 
    }
    .alertify-dialog-inner-confirm,
    .alertify-dialog-inner-prompt {
      padding: 25px; 
    }