Script for centos7 now also installs 'unzip' package

Some virtual server providers (like DigitalOcean) do not have unzip
installed in their centos7 image so we need to install it in our script.

scripts/setup-web2py-centos7.sh

@@ -56,7 +56,7 @@ echo
 yum update
 
 # Install required packages
-yum install httpd mod_ssl mod_wsgi wget python
+yum install httpd mod_ssl mod_wsgi wget python unzip
 
 ###
 ### Phase 2 - Install web2py