Add restic support

There have been no activity on !2 (closed) since one year. So here is a more complete integration of restic.

examples/Makefile.am

 
 EXAMPLES = example.borg example.dup example.maildir example.makecd \
 		example.mysql example.pgsql example.rdiff example.rsync \
-		example.sh example.svn example.sys example.trac
+		example.sh example.svn example.sys example.trac example.restic
 
 EXTRA_DIST = $(EXAMPLES)