This fixes #55

Some explanation of the changes:

• jQuery.getScript doesn't play well with latest CSP security fixes made to Magento, so I replaced it with vanilla JS
• To get nonce value required by CSP (and escape script content properly) I needed to add additional dependencies to the ConfigOpen and ConfigOrigin classes
• Although, these classes (and ConfigFacade) where instantiated directly 'on use', which would require passing long chain of class members only to create these classes, which should be DI's job
• Magento 2 proxies do exactly what you intended to do in the code, so the class is actually instantiated only when used, so I removed the direct instantiations and instead added Proxy classes as members trimming down class dependencies significantly

I'm explaining this in detail as it might seem like a lot of seemingly unrelated code changes for a simple JS fix.