Remove Taverna server code from the engine.

This is all to go in the Orchestrator for the scaling.
Cloud orchestration of Taverna Server (AWS).

Start and stop instances of Taverna Server to run workflows in the Cloud. This
implementation targets AWS specifically.
Support workers in the setup scripts.

add_worker script allows for simple adding of workers and add_workflow script
now gets choice of worker while registering a workflow.
Use the latest version of the t2flow gem.
Rename bin-support.rb to be more consistent.

Fix all references to it too.
Add mysql support.

Via mysql2 gem.