fix and optimize docker-compose with ReactJS building (#306)

* rm node-server/public static frontend assets

The previous build workflow involved manually building the ReactJS
frontend, and then stashing that in the node server.  @suyashkumar has
updated the docker-compose configuration to build this on-the-fly,
making these static assets unnecessary.

closes #304

* fix Docker build

For some reason, using node:latest on my Fedora 30 setup was failing
(issue #305), even though it manually would build the ReactJS frontend
outside of Docker.

Dropping back to using NodeJS 8.x appears to be working, so will limit
to that for now.

fixes #305

software/cloud-dashboard/Dockerfile

@@ -1,4 +1,4 @@
-FROM node:latest
+FROM node:8
 
 # Initialize Workspace
 WORKDIR /app

software/cloud-dashboard/node-server/Dockerfile

@@ -1,4 +1,4 @@
-FROM node:latest
+FROM node:8
 WORKDIR /app
 COPY . /app
 RUN npm install