Webfiles not always reloaded in multi site mode

In multi site mode, the sites begin bootstrapping before the platform has completed initializing. This is a racing issue: ConfigurationServiceImpl#applySiteConfig is sometimes called before ConfigurationServiceImpl#init has completed, and the former requires the WebfilesService to be up and running, a service which is started by the latter.

The applySiteConfig is invoked for every site (webapp) that has completed loading by Tomcat (via org.hippoecm.hst.site.container.HstContextLoaderListener that is a ServletContextListener)