Apply all matching exclusion rules to URLs

This PR an implementation of the idea from [this comment](https://github.com/philc/vimium/pull/1154#issuecomment-60097660).

It modifies the exclusion rule URL matching to consider all possible rules, rather than the first rule found. Hopefully this should give better UX, since we aren't ignoring any rules which the user would expect to be applied.
This is a problem.  The `rule` is cached.  So if you change it like this here, then you're changing the underlying cached object.