Tool Service JSON configuration needs updating for T3

External Tool service has not yet been updated to use JSON configuration. The configuration is a bit complex at the moment, and needs to be simplified (as using Tool is the most likely usecase for Scufl2 outside the Workbench).

This work includes:

• Defining JSON schema for Tool
• Updating Tool Activity
• Updating Tool Activity UI
• Updating SCUFL2 translator