Issue #2376775 by eshta: Fix Acquia Lift Web Admin link href to be dynam...

...ically read from API url configuration setting.
We need to be sure the configured API url does not already include the scheme. Let's make a change in the admin form to strip it out if it's entered. And here we should use whatever scheme is currently being used like we do in the getInstance() method in the api client class, i.e.

        global $is_https;
        // Use the same scheme for Acquia Lift Profiles as we are using here.
        $url_scheme = ($is_https) ? 'https://' : 'http://';
        $api_url = $url_scheme . $api_url;