Low: pgsql: fix string processing of crm_mon's output on Pacemaker 1.1.8

Replication mode dosen't work on Pacemaker 1.1.8
because the output of "crm_mon -n" is different from one
on Pacemaker 1.0.x.

So I fix string processing to work on 1.1.8 and 1.0.12.