PHP 7 compatibilty

Hi there,

I just noticed that the plugin isn’t compatible with PHP 7.
Got this error:

*16251 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Error: [] operator not supported for strings in /var/www/aaa/html/aaa/plugins/google-analytics-for-wordpress/includes/admin/settings/settings-api.php:333

I like the plugin but I can’t use it as it is not compatible with PHP 7.

It would be great if you could make it compatible as soon as you can.

Best regards.