Intial work to add mysql support for director

* Changed director's config format to no use URIs
* Migrate now uses director's configure_db method
* Added drop foreign key constraint to an earlier migration file
* Renamed job template properties to director_db from postgres
* Updated jobs and package for mysql dependencies

[for #49306843]
PowerDNS and Bosh Registry mysql support

* Removed powerdns postgres replication
* Renamed properties to be COMPONENT.db for database properties
* Added db configuration tests for director and registry

[for #49306843]
Fix integration tests for new db configuration format

[#49306843]
Bump sequel gem for drop_foreign_key feature needed for mysql

[#49306843]
Improve readability of deployment plan filter_properties
Convert release database connection options properties to hashes

[#49306843]
Remove powerdns nginx monit config
Update Micro bosh and bootstraped full bosh for new postgres properties

[for #49306843]
Revert "Bump sequel gem for drop_foreign_key feature needed for mysql"

This reverts commit 210de1c460e644ca876a3f3f1efdf242f52711c5.

Bumping to this version of the sequel gem borked the director unit tests
and most of the integration tests.
Fixed mysql migration for dropping constraints

The constraint drop was not needed and in fact does not work on
postgres.