Cherry picked from commit https://svn.astron.nl/LOFAR/branches/RT-Task11326@38649.

Task #8993: Accidentally reverted conflicting changes to Docker directory when merging the trunk (commit r35701), whilst the trunk version should have been adopted.

Task #9192: Use C++11, Ubuntu 16.04, OpenBLAS, AOFlagger 2.8.0, latest casacore/casarest/python-casacore, for increased performance

Task #8887: Reverting back to Ubuntu 14.04, C++98, and fewer optimisations, to avoid AOFlagger crash in NDPPP

Task #8887 #8993: Build lofar Docker images with C++11 and optimisations, use OpenBLAS instead of BLAS+LAPACK, do not build tests, pull casacore from master and casarest from jjdmol/casarest repo until C++11 fixes have been merged to main repo, drop superfluous -DLOG4CPLUS_ROOT

Task #8437: Do not set user id during build, to avoid having to add one. Also, do not run apt-get upgrade as that is unnecessary.

Task #8437: Install /opt/lofar/var als a symlink to /home/lofar/lofar/var and allow only $HOME to change ownership at start. This reduces both image boot time and any changes committed from a container

Task #8437: Create /opt/lofar/var/{log,run} in the Docker image, and transfer ownership of /opt to calling user to allow him to write to /opt/lofar/var.