add datatimePicker for Boostrap 3.0

This is of:  https://github.com/Eonasdan/bootstrap-datetimepicker

these are example of use:  http://eonasdan.github.io/bootstrap-datetimepicker/

for HAML use this code and magically will walk:

 .form-group
      #datetimepicker1.input-group.date
        = f.text_field :start_date, {class: "form-control"}
        %span.input-group-addon
          %span.glyphicon.glyphicon-calendar

Remember to add the js code:

$(document).ready(function(){
  $('#datetimepicker1').datetimepicker();
});