Implement /rangelock

More info: http://www.smogon.com/forums/threads/3517493/
O(n) check? Seems unnecessary. Why isn't the hostname the key of `lockedDomains`?

For reference, this is how hostfilter is implemented:

	exports.hostfilter = function(host, user) {
		var dotIndex = host.lastIndexOf('.');
		if (host.substr(-6) === '.co.uk') dotIndex = host.length - 6;
		if (dotIndex >= 1) dotIndex = host.lastIndexOf('.', dotIndex - 1);
		var shortHost = (dotIndex >= 1 ? host.substr(dotIndex + 1) : host);

		switch (shortHost) {
		case 'zenmate.com':
		case 'pacswitch.com':
		case 'tunnelbear.com':
		case 'redstation.co.uk':
			user.popup("Your IP (host: "+host+") is a known proxy and has been locked.");
			user.locked = '#hostfilter';
		}
	};