Prevent system from starting when a non-UTF-8 filesystem has been detected

Sometimes it happens that tomcat is started with a somehow wrong environment. This can lead to setting the file.encoding property to something else than UTF-8. In such a case filenames written to the filesystem use another encoding. Once the system starts with UTF-8 again, those filenames are broken and can not be recovered. Worst case is to have a mixed filesystem with some UTF-8 files and some ISO-Latin files.

OpenOLAT does already check for UTF-8 capable filesystem, however it does not enforce using this filesystem. This issue implements a system abort when a non-utf-8 filesystem is detected.

This check can be disabled in the olat.local.properties. The new config value is:

# abort system startup when no UTF-8 capable file system is detected. In production this should be set to 
# true to prevent accidental startup with another encoding which leads to a big data mess
enforce.utf8.filesystem=true

This should only be set to false for developer system wich are often set up on OSX or Windows which in most cases do not use UTF-8 by default. For production most likely this should never be set to false!