Docker improvements

- Create run-onionr-node.sh to parse env and supply args to run-onionr-node.py
- Dockerfile:
  - Run onionr by default rather than bash
  - Run as unprivileged user by default instead of root
  - Use /app for all code
  - Specify python 3.7 (3.8 fails to build cffi)
  - Use apt-get rather than apt (apt's CLI is not stable)
  - Slight reformatting and consolidation

Dockerfile

@@ -1,12 +1,12 @@
 FROM python:3.7
+EXPOSE 8080
 
 USER root
 
 RUN mkdir /app
 WORKDIR /app
 
-ENV PORT=8080
-EXPOSE 8080
+ENV ONIONR_DOCKER=true
 
 #Install needed packages
 RUN apt-get update && apt-get install -y tor locales
@@ -26,5 +26,6 @@ VOLUME /app/data/
 #Default to running as nonprivileged user
 RUN chmod g=u -R /app
 USER 1000
+ENV HOME=/app
 
-CMD ["bash", "./onionr.sh"]
+CMD ["bash", "./run-onionr-node.sh"]