Merge tag 'rel-0.8.1' into develop

Tagged rel-0.8.1
Use official Java image as base

The official java image basically does the same as yor first RUN command, so if you use that as base, downloads will be faster (because most people already have the java image available locally) and it shortens the dockerfile.
Changed base image to java:7-jre
Merge pull request #32 from lorenz/patch-1

Use official Java image as base
Reading is hard. Let's use fewer words.
Merge pull request #34 from pblittle/feature/readme-tweaks

Reading is hard. Let's use fewer words.
Bump version to 0.9.0
Merge branch 'release/rel-0.9.0'