Apply user options for each select element

Fixes #4
adding a class to the dd-slick container element when the list is open, to allow for different styling of the box when the list is open.
Use original id attribute for new input element
Merge pull request #34 from jlbruno/master

Adding dd-open class to list container when list is open
Merge pull request #31 from peterbee/master

Thanks! This fixes for multiple selects bug #4.
Fix #35 typo and add onOpen and onClose callbacks.