Replace felix/openjdk with ubuntu:12.04, install openjdk-7-jre-headless
Remove dpkg-divert initctl

Fixed in the current ubuntu:12.04 image:
$ docker run -it ubuntu:12.04 ls -l /sbin/initctl
lrwxrwxrwx 1 root root 9 Apr 25 02:43 /sbin/initctl -> /bin/true
Use official centos:centos6 instead
Merge pull request #6 from manics/specify_versions

Specify versions of upstream images