Bugfix - dataToOptions

Hi, I use your repository as submodule in my gem. This gem packages your bootstrap-datetimepicker for Rails asset pipeline, and creates the Simple Form custom fields out of the box. My SimpleForm custom field implementation assumes to work the data-date-* attributes correctly in your picker. I find out that, there is a bug in your dataToOptions function, and I have prepared this pull request to fix that issue. Please, accept this request.