Re-initialize apiUmbrellaWeb instance when API Umbrella settings change

[brylie]

The apiUmbrellaWeb object is not being re-initialized when settings change. This means, that any errors in configuration remain even after updating the configuration page.

[brylie]

An alternative approach would be to initialize the apiUmbrellaWeb inside of any server method where it is used. This would avoid having to manage a global apiUmbrellaWeb object.