Dapps interface RPC (#3311)

* Dapps Interface RPC

* Adding JS apis

* Support for signer interface in proxypac and embeds

* Fixing tests

* fixing tests again


Former-commit-id: 7b998f7ebf1f13bc8e2d948ae896b78e5870b53a

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

@@ -60,6 +60,11 @@ export default class Parity {
       .then(outNumber);
   }
 
+  dappsInterface () {
+    return this._transport
+      .execute('parity_dappsInterface');
+  }
+
   defaultExtraData () {
     return this._transport
       .execute('parity_defaultExtraData');

js/src/jsonrpc/interfaces/parity.js

@@ -109,6 +109,15 @@ export default {
     }
   },
 
+  dappsInterface: {
+    desc: 'Returns the interface the dapps are running on, error if not enabled',
+    params: [],
+    returns: {
+      type: String,
+      desc: 'The interface'
+    }
+  },
+
   defaultExtraData: {
     desc: 'Returns the default extra data',
     params: [],