Provide the idea of a demo mode to the gui.

- Enable passing a url param to the api calls for getting icons.
- This will enable manually overriding the icon safety checks for the purposes
of a demo which has been sanity checked by the presenter.
Merge pull request #102 from mitechie/demo-mode

- Enable passing a url param to the api calls for getting icons.
- This will enable manually overriding the icon safety checks for the purposes
of a demo which has been sanity checked by the presenter.