Update vue.js app with UI to handle scopes

the Scope (e.g. the white-label travel agent) will be chosen from the URL route.

major parts of the frontend might therefore just consist of:

• plumbing to the backend
• looking in the agent Scope for minimal white-label details (e.g. an HTML description / logo / css for background colour?)
• a page (possibly within the docs site rather than the app?) with links to the 2 agent Scopes