install.sh: centos hacks, make executable, include parameters.isc

Caché looks in /etc/redhat-release to identify if this is a Red Hat
distro using a specific string. The script auto-hacks the
/etc/redhat-release to match what Caché needs to install silently then
revert it back when finished

Make install.sh executable

Include parameters.isc which is the automated script install.sh uses