Update to GTM 6.0-002

Update the installer script to install GTM 6.0-002 by default
Add credits for GDE config, and correct shell for VistA user

The -s option for useradd was missing and the foia user was getting an
incorrect shell (/bin/sh) instead of the intended shell (/bin/bash).

Included thanks to the VistA community including Gus Landis and Sam Habiel for
the GDE configuration.
Update PATH and gtm_zinterrupt environment variables

Add GT.M to path. This allows OSEHRA's VistA Automated Testing
environment to run (uses an exec internally) and adding GT.M to the PATH
is how things should be done.

gtm_zinterrupt is code that is executed by GT.M to examine the detals of
a VistA process.