Dapp refresh (#5752)

* RwLock

* getting there

* argh

* parking_lot

* rpc

* wax on wax off

* almost there

* remove lock

* write over read

* works

* linting

* small updates

* dissapearing act

* router update

* complete

* one m

* grumbles1

* grumbles part II

* parking_lot->util

* missed test case

* fied package-lock.json

* small fixes

* 404 tests failing

* cleanup

* cleanup 2

* updates and the likes

* play

* simplify filter

* f-ing bugs

* read->write

* Address own grumbles.

* Fix test.

dapps/src/tests/fetch.rs

@@ -39,7 +39,7 @@ fn should_resolve_dapp() {
 
 	// then
 	response.assert_status("HTTP/1.1 404 Not Found");
-	assert_eq!(registrar.calls.lock().len(), 2);
+	assert_eq!(registrar.calls.lock().len(), 4);
 	assert_security_headers_for_embed(&response.headers);
 }