Update Dockerfile to use gunicorn for python3 to resolve encoding errors

Dockerfile

@@ -3,7 +3,8 @@ FROM ubuntu:latest
 MAINTAINER Ulrik Djurtoft "ullebe1@gmail.com"
 
 RUN apt-get update -y && \
-    apt-get install -y python-pip python-dev python-virtualenv gunicorn
+    apt-get install -y python3-pip python3-dev python3-virtualenv 
+RUN pip3 install gunicorn
 
 # We copy just the requirements.txt first to leverage Docker cache
 #COPY ./requirements.txt /app/requirements.txt
@@ -25,10 +26,10 @@ COPY gunicorn_config.py /deploy/gunicorn_config.py
 COPY dagensdatalog.py /deploy/app/dagensdatalog.py
 COPY templates /deploy/app/templates
 COPY ./requirements.txt /deploy/app/requirements.txt
-RUN pip install -r /deploy/app/requirements.txt
+RUN pip3 install -r /deploy/app/requirements.txt
 WORKDIR /deploy/app
 
 EXPOSE 80
 
 # Start gunicorn
-CMD ["/usr/bin/gunicorn", "--config", "/deploy/gunicorn_config.py", "dagensdatalog:app"]
+CMD ["gunicorn", "--config", "/deploy/gunicorn_config.py", "dagensdatalog:app"]