Add Dockerfile based on Ubuntu 16.04

The official Dockerfile on alpine:3.11 doesn't work on Raspberypi OS (RPI4), this works fine

Dockerfile.ubuntu

@@ -0,0 +1,47 @@
+FROM ubuntu:20.04
+
+#Timezone settings
+ENV TZ=Etc/UTC
+RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
+
+#Install dependencies
+RUN apt update \
+ && apt install -y python3-pip tor openssl \
+ gcc libffi-dev musl-dev make \
+ pkg-config
+
+#Setup Tor
+RUN echo "ControlPort 9051" >> /etc/tor/torrc \
+ && echo "CookieAuthentication 1" >> /etc/tor/torrc
+
+# Set up a non-root user
+RUN useradd --uid 1000 --shell /bin/bash --create-home znuser
+WORKDIR /home/znuser
+
+#Add Zeronet source
+COPY . .
+VOLUME /home/znuser/data
+RUN chown znuser:znuser -R data
+
+USER znuser
+ENV PATH="/home/znuser/.local/bin:${PATH}"
+
+RUN pip3 install virtualenv \
+ && virtualenv zeroenv \
+ && . zeroenv/bin/activate \
+ && pip3 install -r requirements.txt
+
+RUN . zeroenv/bin/activate \
+ && python3 -V \
+ && python3 -m pip list \
+ && tor --version \
+ && openssl version
+
+#Control if Tor proxy is started
+ENV ENABLE_TOR false
+
+#Set upstart command
+CMD (! ${ENABLE_TOR} || tor&) && . zeroenv/bin/activate && python3 zeronet.py --ui_ip 0.0.0.0 --fileserver_port 26552
+
+#Expose ports
+EXPOSE 43110 26552