seednode: remove some files, add dockerfile and readme with instructions

seednode/docker/Dockerfile

@@ -0,0 +1,29 @@
+# docker run -it -p 9050 -p 2002 --restart-policy unless-stopped --name haveno-seednode haveno-seednode
+# TODO: image very heavy, but it's hard to significantly reduce the size without bins
+
+FROM openjdk:11
+
+RUN set -ex && \
+    apt update && \
+    apt --no-install-recommends --yes install \
+        make \
+        git \
+        tor
+
+RUN set -ex && adduser --system --group --disabled-password haveno && \
+    mkdir -p /home/haveno && \
+    chown -R haveno:haveno /home/haveno
+
+USER haveno
+
+WORKDIR /home/haveno
+
+RUN set -ex && git clone https://github.com/haveno-dex/haveno.git && \
+    cd haveno && \
+    make skip-tests
+
+WORKDIR /home/haveno/haveno
+
+ENTRYPOINT [ "./haveno-seednode" ]
+
+CMD ["--baseCurrencyNetwork=XMR_STAGENET", "--useLocalhostForP2P=false", "--useDevPrivilegeKeys=false", "--nodePort=2002", "--appName=haveno-XMR_STAGENET_Seed_2002" ]