Smarter Tokens fetching (#3546)

* Don't auto-subscribe for contracts #3240

* Smarter Balance : don't re-instantiate contracts, fetch tokens #3240

* Smarter Balance Tokens fetching (update image when needed) #3240

* Attaching to TokenReg Events instead of fetching for each block #3240

* Unsubscribe from shapeshit... #3240

* Unsubscribe from EthFilter if used once (resolved) #3240

* Remove warning

* PR review fix

* Typo

* Better contract JS API : one subscribe for all #3546

* Fixed test

js/test/mockRpc.js

@@ -23,9 +23,10 @@ export const TEST_HTTP_URL = 'http://localhost:6688';
 export const TEST_WS_URL = 'ws://localhost:8866';
 
 export function mockHttp (requests) {
+  nock.cleanAll();
   let scope = nock(TEST_HTTP_URL);
 
-  requests.forEach((request) => {
+  requests.forEach((request, index) => {
     scope = scope
       .post('/')
       .reply(request.code || 200, (uri, body) => {