Update Ubuntu script to match version restrictions of current PyNE

[gonuke]

In preparing for the PyNE 0.7.6 release, we discovered some changes in the python installation world that may break our scripts. Hopefully this provides a good temporary fix.

Testing in the ubuntu script before modifying the docker files....

Hoping to fix #64

[ahmadMIbrahim]

I do not see the PyNE PYTHONPATH defined in gonuke:update_ubuntu_build.

When I run the script without defining my own PYTHONPATH, I encounter the same error I used to have while running the tests file, travis-run-tests.bash. This error is:
ModuleNotFoundError: No module named 'pyne'.

I tried to add my PYTHONPATH to point to the folders that include .py files in the new/fresh installations that the script has already made. On my system, these are:
PYTHONPATH=$HOME/anaconda3/lib/python3.7/site-packages/pip/_vendor/:$PYTHONPATH
PYTHONPATH=$HOME/.local/lib/python3.7/site-packages/:$PYTHONPATH
PYTHONPATH=$HOME/opt/moab/lib/python3.7/site-packages/pymoab-5.1.0-py3.7-linux-x86_64.egg/:$PYTHONPATH
PYTHONPATH=$HOME/opt/openmc/:$PYTHONPATH

I am getting much better response than before. I see most of the tests passing, but some did not pass. Some of the errors I am getting are related to OpenMC such as "NameError: name 'openmc' is not defined." It is worth mentioning that I had commented the "exit $status" line in travis-run-tests.bash to allow the script to run until the end.

Thank you very much. I feel I am in better state now.

[ngranda]

LTGTM. My only comment is to remove a duplicate line