uses page:change and document ready in js
make foundation init compatible with turbolinks
- page:change runs on ready and on page change
- binding as $(document).ready() is preferable to $(document).on('ready', ...)
correct event bindings with jquery-turbolinks
use the same id for every song form
- reason: to keep declarations dry
- warning: now this form should only be used once on each page
correct js loading for turbo links
see: https://github.com/rails/turbolinks
validate empty song and playlist fields in js