Date range select mismatch prevention

I had taken changes Hana(@naisnouk) had made and upgraded the javascript plugin so it will not allow user to pick end date greater than start date and both of them are restricted to date less than today.

In addition I had written cleaned data method where is taken care of this same issue on a server side error. This is in case someone is using manual input and not trough plugin. To provide easier input like that (disabled people often can not use a mouse) I had put just a simple placeholder to inputs to instruct user about the format of the date input they should use.

Fixes issue #117