Add EXO proxy setup for new apps

[spacerockzero]

• Added fs-webdev/exo as a dev dep. It will be used for any front-end stack code the apps start out with
• exo/proxy will handle the localdev service and auth proxy
• apps generated will have an extendable setupProxy file that extends the default proxy list and config's smart defaults
• docs for how to use and extend the proxy configs are here: https://github.com/fs-webdev/exo#proxy
• apps generated will now be able to navigate to /auth login, and will have an fssessionid cookie saved on localhost domain when it redirects back to localhost
• NOTE: Auth service security whitelist requires the local app to run on PORT 5000, until we can get them to change the whitelist, I've prepended PORT=5000 to scripts > start, otherwise we'd get a token error when contacting auth service.
• Existing apps will need to prepend PORT=5000 to the npm start script in their package.json