system report: skip irrelevant files in /etc/pmg/templates

system report: skip irrelevant files in /etc/pmg/templates

This patch removes:
* templates which have no changes to the ones in
  /var/lib/pmg/templates
* files generated by ucf

from the report. Unmodified files are reported, so that the user can
remove them.

This should make providing support a bit easier - as currenlty I'd
copy each template from the report to `diff` it with the version in
the package, for finding out if there is something relevant.

the new dump_template sub was copied from dir_to_text, in order to
explicitly write which files are skipped.

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
 [T: merge in helper method for getting the unmodified templates ]
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>