Part of #348
Aug 14 19:10:46 collectd[12651]: close failed in file object destructor: Aug 14 19:10:46 collectd[12651]: IOError: [Errno 10] No child processes
The built-in df plugin cannot do the following: * if we choose by type ext4, we want to skip devicemapper (on scaleway) * the MountPoint of the appsdata directory is not possible to know at install time Fixes #398