Fix issue that broke SiteConfigAdmin

As described in issue #1 there was an issue that could prevent loading the SiteConfigAdmin and breaking script tags

1.2

Fixed several issues, added QoL adjustments

Fixed

• The SilverStripe Requirement API was being utilised before, which caused some strange issues sometimes
• Instead the required js will now be loaded with a config yaml file

QoL

• setTheme and setMode methods got adjusted
  • you can now use either setMode("ace/mode/html") or simply put setMode("html")