added support for reuse of existing snackbars
added support for reuse of existing snackbars

- adds data attributes to snackbar for use later (content, style, timeout, htmlAllowed)
- adds ability to create snackbars with specific ids from javascript
- uses data attributes from snackbar to properly reapply
- will not close and reopen snackbar if already opened (only moved to bottom of stack)

FezVrasta/snackbarjs,gdseller/snackbarjs