Add plugin for checking the mount points of a filesystem

This is similar to the community plugin of the sma ename but has increased functionality

It is also able to check mount points by parsing '/proc/self/mounts' and trying to write/read a tempfile in each mount point found

It still has some issues with it, I would like to be able to get mounts from all namespaces at some point in time and also have the 'dir' option be an array instead of a single value