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.

js/src/api/rpc/parity/parity.js

@@ -95,6 +95,11 @@ export default class Parity {
       .execute('parity_dappsList');
   }
 
+  dappsRefresh () {
+    return this._transport
+      .execute('parity_dappsRefresh');
+  }
+
   dappsUrl () {
     return this._transport
       .execute('parity_dappsUrl');