Prevent code dynmamically pulling in CDAT's libz...

First let me explain...  this is regarding git or any program that
dynamically loads the libz library. If it gets the lib from CDAT's
installed/built libz (as posted in the LD_LIBRARY_PATH, written to
etc/esg.env and sourced at the top of this script) it will result
in the following warning:

/usr/local/uvcdat/Externals/lib/libz.so.1: no version information available (required by git)

The easiest and least invasive thing to do is to remove or rename
CDAT's libz.  So that is what we are doing here.  CDAT should not
have built its own libz in the first place, if there is libz
already on the system.  So this bit of hacking in most clean
install scenarios is moot (though it in-turn means you have to
install libz on your system to get past, at least git building).

Charles made me do it ;-)
updated version of security to 2.4.0