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.
We no longer need fpm

We are doing agent updates as gems.

[finishes #49812867]
Revert deb based agent update

* [#49035201]
* We will use gems to update agent for development
Rename file to match only task
Implicitly abort with sh and remove unused require
[#49035201] Introduce rake bosh_agent:update

* Quicker dev cycle
* Updates by building and publishing a new bosh_agent gem
[bosh_agent] readme for configuration of bosh_agent CLI
[bosh_agent] readme intro & API documentation
[bosh_agent] readme clarification on nats vs https

bosh_agent does not currently support both nats & https API modes
[director] Better message for instance changes [fixes #47553839]
[fixed #50196677] 'bosh aws create' migrations are stored in more unique S3 bucket