add jdk12

[davidkarlsen]

Offer jdk12

---

This change is 

[vvanholl]

In order to make it work, you must add these lines

RUN yum update --assumeyes && \
    yum install --assumeyes wget unzip && \
    yum clean all

ENV LANG=en_US.utf-8
ENV LC_ALL=en_US.utf-8

[vvanholl]

I also forgot package procps

[vvanholl]

In reality this is very difficult since jdk12 switched to Oracle Linux in place of Debian

[vvanholl]

And I am sure other components could miss :(

[keeganwitt]

Are you sure they switched to Oracle Linux? My interpretation was that there just wasn't a Debian package available yet. Did you see any announcements on the topic?

[keeganwitt]

If you have no objection, I'll close this in favor of #98. However, if you have a reason you need Oracle Linux, we can consider adding that as well (I mentioned that possibility in #91, though no one has expressed interest so far).

[davidkarlsen]

I think I'd stay away from anything with Oracle in its name - you never know when they change the terms and into what - but the track record the later years has been very hostile.