HSM: renamed archive_num to archive_id, as Lustre/HSM commands.
purge policies: disabling purge if no purge policy is defined.
policies: last_archive > N should not match never archived files.

The convention is (last_archive == 0) IF-AND-ONLY-IF file has never
been archived, so (last_archive > Ndays) should not match never
archived files.
packaging/config: take --sysconfig and --prefix into account in binaries.

The robinhood binaries must take those parameters into account to search for config files.
init.d script and RPM package must also use these values.

Added script "scripts/check_rpm_reloc.sh" to test this with various combinations
of these parameters.