Autoscaling "cores" tag should support "strict : false"

Currently when the "cores" global tag is parsed the parser automatically refuses to accept any other attributes - and since the "strict" attribute defaults to true there's no way to relax this rule.

This becomes important when trying to spread the cores evenly across the cluster - even minor variations will generate violations, while in most cases a good enough spread is sufficient.

It appears there's no other reason for this limitation apart from the rule parser limitation.