account better for preset values in shells

While we can inhibit all startup scripts in bash, zsh will always load
~/.zshenv.  Account for this in the shell test by checking the values
from the shell without applying any of our own changes.
update quoting routines for EUMM 7.0

The new EUMM takes options like INSTALL_BASE as strings rather than
passing them through the shell.  Remove our extra level of quoting that
was accounting for that, and bump the EUMM prereq.