Fix ceilometer collector dispatcher on SLES

Follow the guide on SLES SP3 without ceilometer collector dispatcher
configured, it will print nothing when verify with
`ceilometer meter-list`, because the ceilometer-collector catches an
exception of `RuntimeError: No ceilometer.dispatcher extensions found`

This patch add a step for SLES to configure default ceilometer
collector dispatcher to `database`.

Change-Id: Ib2dade0a6f382ec43eac64374e5977df81a48b61
Closes-Bug: #1267318
Merge "Fix ceilometer collector dispatcher on SLES"