Fix NC-1848 by removing the unused Dockerfile (#214)

Since docker image is now provided in the Jenkins build process repos, this
image is not used anymore and may confuse users as it doesn't behaves the same
way as the one we published on Docker Hub
Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

Dockerfile

@@ -1,42 +0,0 @@
-# Pantheon release grade Docker image
-#
-# What is this image for ?
-#   This image is for using Pantheon within Docker for any purpose, test, dev, production.
-#   The Docker file integrates two steps, first the build with a JDK and then the runnning image with a JRE.
-#   Then you don't need a JDK installed locally to build Pantheon, just run the docker build
-#   command and once the image is created you can use it as if you were using a regular Patheon binary.
-#
-# How to use this image:
-#
-#   first build it (use the name and tag you like) :
-#
-#   docker build -t mypantheon:myTag .
-#
-#   then run pantheon:
-#   Either as a simple node with sync on mainnet with a volume for data (keeps the database between runs) and that's all:
-#
-#   docker run -d --mount source=pantheon_database,target=/opt/pantheon/database --name myPantheon mypantheon:myTag
-#
-#   or as a simple node with sync on mainnet with a volume for data (keeps the database between runs) and  HTTP/WS RPC access :
-#
-#   docker run -d --mount source=pantheon_database,target=/opt/pantheon/database \
-#   --name myPantheon -p 8545:8545 -p 8546:8546 mypantheon:myTag \
-#   --rpc-enabled --rpc-listen=0.0.0.0:8545 --rpc-cors-origins=mydomain.tld \
-#   --ws-enabled -ws-listen=0.0.0.0:8546
-
-# builder temporary image with JDK
-FROM openjdk:8-jdk-slim as builder
-# copy all pantheon source to the image
-COPY . /tmp/pantheon
-WORKDIR /tmp/pantheon
-# build the distribution
-RUN ./gradlew installDist
-
-# final image with only jre
-FROM openjdk:8-jre-slim
-# copy application from builder image
-COPY --from=builder /tmp/pantheon/build/install/pantheon /opt/pantheon/
-# List Exposed Ports
-EXPOSE 8546 8545 30303
-# specify default command
-ENTRYPOINT ["/opt/pantheon/bin/pantheon"]