Adds dependencies needed to setup new webserver

Some of these may be server-specific, and therefore maybe shouldn't be
committed. If that is the case, then remove them before merging this
commit into main.
Move production-specific Ubuntu packages to separate file
Update install instructions for base/prod packages

Also took out some Dropbox specific stuff now that we aren't
using Dropbox anymore.
Merge pull request #864 from learning-unlimited/server-dependencies

Adds dependencies needed to setup new webserver