Added docker to run tests on various mono versions

docker/tests/mono/complete/Dockerfile

@@ -0,0 +1,22 @@
+FROM ubuntu:xenial
+
+ENV DEBIAN_FRONTEND noninteractive
+ARG MONO_VERSION=5.20
+ARG MONO_URL=stable-xenial/snapshots/$MONO_VERSION
+
+RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF && \
+    echo "deb http://download.mono-project.com/repo/debian $MONO_URL main" > /etc/apt/sources.list.d/mono-official-stable.list && \
+    apt-get update && apt-get install -y \ 
+        tofrodos tzdata \
+        mono-complete \
+        sqlite3 mediainfo \
+        && rm -rf /var/lib/apt/lists/*
+
+COPY startup.sh /startup.sh
+RUN  fromdos /startup.sh
+
+WORKDIR /data/
+VOLUME ["/data/_tests_linux", "/data/_output_linux", "/data/_tests_results"]
+
+CMD bash /startup.sh
+