Update docs with new dbsync command

The ironic-dbsync utility was updated with a new 'create_schema'
command with this review:

https://review.openstack.org/107629

This updates the quickstart guide to use this new command. We also
change the deploy guide to use it, mainly for consistency of usage
in our documentation.

Change-Id: I2b0e8620c1143822c1ba263d4004499ad5ea9cff
Closes-Bug: #1347604
Merge "Update docs with new dbsync command"