Tidy up variable initialisation

Sort things by category, and organise everything in the same place.
We don't support reuse of RFB objects so we can safely init everything
in the constructor.

tests/test.rfb.js

@@ -459,12 +459,6 @@ describe('Remote Frame Buffer Protocol Client', function() {
             var client;
             beforeEach(function () { client = make_rfb(); });
 
-            it('should reset the variable states', function () {
-                sinon.spy(client, '_init_vars');
-                client._updateConnectionState('connecting');
-                expect(client._init_vars).to.have.been.calledOnce;
-            });
-
             it('should actually connect to the websocket', function () {
                 sinon.spy(client._sock, 'open');
                 client._updateConnectionState('connecting');