Fix incorrect spellings & capitalizations

[kingIZZZY]

Repetitive code has mistakes trying to find array value by varying key spellings & capitalizations:

        } else if(array_key_exists('redirecturi', $settings)){ // ends with "I"
            return $settings['redirecturl'];                   // end with "L"
        } else if(array_key_exists('redirectUri', $settings)){ // ends with "I"
            return $settings['redirectUrl'];                   // end with "L"

Replaced logic with standardized util method to eliminate such mistakes.