BUGFIX Javascript and CSS not provided when cached

* Added shortcode option variable names on Settings screen
* Added validate case is_true
* BUGFIX Javascript and CSS not carried through when testimonials are cached
* Default `do_shortcode` on
* Refactored CSS/JS generation and inclusion
* Refactored scripts and styles handling
* Scripts `ksort` removed. Use `array_unshift` in your `testimonials_widget_testimonials_js` filters instead.