feat(Modeler): expose Viewer and NavigatedViewer constructors

This allows bundled users (f.ex without browserify)
to use the modeler + viewers easily without having to monkey patch or
load more than one bundled file.

Closes #541

lib/Modeler.js

@@ -6,6 +6,8 @@ var Ids = require('ids');
 
 var Viewer = require('./Viewer');
 
+var NavigatedViewer = require('./NavigatedViewer');
+
 var initialDiagram =
   '<?xml version="1.0" encoding="UTF-8"?>' +
   '<bpmn:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ' +
@@ -118,6 +120,10 @@ inherits(Modeler, Viewer);
 
 module.exports = Modeler;
 
+module.exports.Viewer = Viewer;
+
+module.exports.NavigatedViewer = NavigatedViewer;
+
 /**
  * Create a new diagram to start modeling.
  *

test/spec/ModelerSpec.js

@@ -399,4 +399,16 @@ describe('Modeler', function() {
 
   });
 
+
+  it('should expose Viewer and NavigatedViewer', function() {
+
+    // given
+    var Viewer = require('../../lib/Viewer');
+    var NavigatedViewer = require('../../lib/NavigatedViewer');
+
+    // then
+    expect(Modeler.Viewer).to.equal(Viewer);
+    expect(Modeler.NavigatedViewer).to.equal(NavigatedViewer);
+  });
+
 });