Fix Dockerfile

[ndahlquist]

These are the code changes we needed to make in order to get the app to work correctly from the Dockerfile. Unfortunately I had to move the directory structure, so feel free to close this if you think it is not a good change

[mridulgain]

Instead of ubuntu why not use node as base image?

[ndahlquist]

Not sure; we didn't spend too much time optimizing, just wanted to fix the functionality.

For what it's worth, the old Dockerfile also appears to use ubuntu as the base.