Output the config filename containing a modprobe alias in XML

Output the config filename containing a modprobe alias in XML

This change affects the XML output:

/operatingsystems/operatingsystem/modprobealiases/alias/text() =>
/operatingsystems/operatingsystem/modprobealiases/alias/modulename/text()

Additionally there are two new elements:

/operatingsystems/operatingsystem/modprobealiases/alias/augeas
/operatingsystems/operatingsystem/modprobealiases/alias/file

These contain information about the location of the alias directive.
/augeas is an augeas path. /file is the path of the file containing the
directive.