RPCs for mode change (#3002)

* Allow warnings.

* Add RPCs to allow ad-hoc mode changes.

* Add the JSAPI interfaces

* Add missing file.

js/src/api/rpc/ethcore/ethcore.js

@@ -91,6 +91,11 @@ export default class Ethcore {
       .then(outNumber);
   }
 
+  mode () {
+    return this._transport
+      .execute('ethcore_mode');
+  }
+
   netChain () {
     return this._transport
       .execute('ethcore_netChain');
@@ -161,6 +166,11 @@ export default class Ethcore {
       .execute('ethcore_setMinGasPrice', inNumber16(quantity));
   }
 
+  setMode (mode) {
+    return this._transport
+      .execute('ethcore_setMode', mode);
+  }
+
   setTransactionsLimit (quantity) {
     return this._transport
       .execute('ethcore_setTransactionsLimit', inNumber16(quantity));