Deactive file ignore for hidden file and add OpenCms cache clear after VFS resource syncronization

1. Deactive file ignore for hidden files to provide syncronization
possibility for resources, started with "." in Linux, like ".content",
".config", etc.

2. Add OpenCms cache clear after VFS resource synchronization to prevent manual clear of OpenCms cache each time after synchronization.

Note: webappDirectory parameter of vfs-maven-plugin must be folder of OpenCms application deployed on web application server (like Apache Tomcat), not default project folder.