Add nprogress files.
Load up nprogress styles and scripts.
Add progress function.
Setup on/off in general options.
Add helper functions and css/html/js.
Fix script naming.
Check if enabled, if so, add html, css, and js.
Clean up.
Re-order general options panel.
Merge branch 'add-nprogress' of github.com:tlongren/independent-publisher into tlongren-add-nprogress
Use Link Color for progress bar color
Use default theme colors for progress bar
Clean up Progress Bar code in functions.php
Add license info for NProgress progress bar code