Sat5: Increase PostgreSQL checkpoint_segments (from Paul Wayper)

[jhutar]

Messages in /var/lib/pgsql/data/log/*log of the form:

checkpoints are occurring too frequently (294 seconds apart) Consider increasing the configuration parameter "checkpoint_segments".

See section 18.5.2 of ​http://www.postgresql.org/docs/9.2/static/runtime-config-wal.html