Enable easy first five minute CX with docker images

[amcp]

Right now, it is difficult for people to get started with JanusGraph as we have not made an official release. To hold over the community until that happens, lets make it easy for people to get up and running on JanusGraph:

mvn clean package -Pjanusgraph-release -Dgpg.skip=true -DskipTests=true
cd janusgraph-dist && mvn install -Pjanusgraph-docker -DskipTests=true docker:build
docker run -d -p 8182:8182 --name janusgraph janusgraph/server:latest
docker exec -i -t janusgraph /var/janusgraph/bin/gremlin.sh

[amcp]

One comment wasn't addressed. We should tell Gremlin Server to listen on 0.0.0.0. I think I've been burned by that in the past.

[sjudeng]

Issue resolved by #308