docker: Update QEMU/Robot docker to bionic

Artful has gone end of release and will no longer build in docker due to
this. Update to the LTS.
easy_install was deprecated in bionic so use pip3 for all package
installations now.
The latest robot uses python3 so adjust our call to use that.
ipmitool in bionic is at 1.8.18 and I verified it works against our
latest master code on witherspoon so just apt-get that package.

Testing:
Ran through run-qemu-robot-test.sh and verified it passed. Did get some
warnings the test team will need to look into but everything still
passed:

Error in file '/tmp/root/11554/obmc-robot/tests/ipmi/test_fru.robot': Escaping empty cells with '\' before line continuation marker '...' is deprecated. Remove escaping before Robot Framework 3.2.

Change-Id: I16268b4042c31ca71cf6db9f37c85f66f65d4606
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
2 files changed