Update Dockerfile for new packaging

Dockerfile

 FROM alpine:latest
 
-COPY uus /uus
+COPY . /uus
 
 RUN apk add -U python3 py3-gunicorn && \
     pip3 install /uus && \
     rm -Rf /uus
 
+ENV FLASK_APP=uus
+
 EXPOSE 8000
 
 ENTRYPOINT gunicorn -b 0.0.0.0 -w 4 uus:app