Use ubuntu-contributed AMIs, not marketplace ones
Merge pull request #136 from Metaswitch/non-marketplace-amis

No Reviewer Required - Use ubuntu-contributed AMIs, not marketplace ones
Add a CDF line to config template]
code review markups
Merge pull request #137 from Metaswitch/sto851

[Reviewer:AMC] Add a CDF line to config template
Make 'knife dns records delete' remove per-node records
Move delete_record method next to create_record and improve its logging
Delete DNS records on scale-down
Merge pull request #138 from Metaswitch/node_dns_deletion

[Reviewer: Andy] Last bit of per-node DNS entry deletion