NEW_RELIC_APP_NAME constant should be optional and taken from the ini file instead

[lucasiturbide]

In NewRelic for PHP configuration file you can define the app name and should not be overridden by the Plugin.
If it's not defined then you could try to fetch it from the INI value newrelic.appname like this:

            $newrelic_app_name = ini_get("newrelic.appname");
            if (!empty($newrelic_app_name)) {
                defined('NEW_RELIC_APP_NAME') or define('NEW_RELIC_APP_NAME', $newrelic_app_name);
            }

[Spriz]

@lucasiturbide We're actually changing the name depending on multiple factors as env (qa/staging/prod) and cli/web