Update deploy_idp.sh

OS type is loaded using lsb_release command: 
files/script.bootstrap.functions.sh:	lsbBin=`which lsb_release 2>/dev/null`

Centos 7 doesn not include redhat-lsb-core package in the default installation, so in the case of Centos 7 the installer will not be able to find the OS type.