Merge pull request #140 from jplock/jp-postgres-pid

PostgreSQL 9.1 installs its pid into a different folder than 9.2

roles/monitoring/files/etc_monit_conf.d_pgsql

-check process postgres with pidfile /opt/postgresql/9.2/main/postmaster.pid
+check process postgres with pidfile /var/run/postgresql/9.1-main.pid
   group database
   start program = "/etc/init.d/postgresql start"
   stop program = "/etc/init.d/postgresql stop"