Using Python3 on CIMS Servers

All versions of python-3.x should be invoked using the binary name
"python3" instead of just "python".
If, for example, a user logged into a CIMS server enters
"module load python-3.5.2"  and then types "python,"
they would end up using the python in /usr/bin/python (python2.6.6).

This is in keeping with the convention that "python3"
be used to invoke all versions of python 3.x
and with the expectation that both python2 and python3 
should be able to coexist -- even within
the same terminal (after a module load).

Python as the name for a python3 binary is not valid
and goes against the convention set out by the python developers.
For example, the header of a python file using v3.5 might look like: