Use postgresql as database for webstatus

pica-webstatus/Dockerfile

@@ -6,6 +6,7 @@ ENV PYTHONUNBUFFERED 1
 
 RUN apt-get update \
     && apt-get install -y --no-install-recommends \
+    postgresql-client \
     gcc \
     gettext \
     libssl-dev \

pica-webstatus/requirements.txt

 Django==1.11
-mongoengine>=0.12.0
 requests
+psycopg2