Add additonal relevant checks to Icinga monitoring

Add additonal relevant checks to Icinga monitoring

Checks added include:

check_postgres.pl (bloat, io, autovacuum freeze, db backends, etc.)
check_procs (apache2, perl SIPServer.pm, Clark Kent)
check_cpu.sh (cpu I/O information)

Added libcache-memcached-perl and memcached packages to be installed on monitor
servers in order for check_memcached.pl to work.

Require "trust" authentication in pg_hba.conf for local connections so
check_postgres.pl can work, otherwise password would be passed over
NRPE in plain text.

Signed-off-by: Michael Peters <mpeters@emeralddata.net>