The vfs_rump plugin enables access to block device backed file systems
supported by the rump kernel. A single rump kernel is in use for any
number of <rump> nodes. The configuration node needs two mandatory arguments:

The 'fs' attribute specifies the file system type, and 'ram' limits the memory
the plugin will use internally. The optional attribute 'writeable' specifies if
the mount is read only or writeable; 'writeable' defaults to true.
