Fixed turbolinks compatibility

Hi,

I'm using this bundle in project with turbolinks and I was getting javascript error `Uncaught ReferenceError: render_datetime is not defined`, when I visit page with datatable by clicking on link via turbolinks (standard browser refresh works normally).

I've fixed it by moving block `sg_datatable_render_functions` block on top of datatable initialization. I'm not sure if this change of order does not affect other funcionality, but everything worked well so far.