Fix transitions between components

assets/js/src/newsletters/newsletters.jsx

@@ -25,9 +25,9 @@ if(container) {
       <Route path="/" component={ App }>
         <IndexRoute component={ NewsletterList } />
         <Route path="new" component={ NewsletterTypes } />
-        <Route name="standard" path="new/standard" handler={ NewsletterStandard } />
-        <Route name="welcome" path="new/welcome" handler={ NewsletterWelcome } />
-        <Route name="template" path="template/:id" handler={ NewsletterTemplates } />
+        <Route name="standard" path="new/standard" component={ NewsletterStandard } />
+        <Route name="welcome" path="new/welcome" component={ NewsletterWelcome } />
+        <Route name="template" path="template/:id" component={ NewsletterTemplates } />
         <Route path="send/:id" component={ NewsletterSend } />
         <Route path="*" component={ NewsletterList } />
       </Route>

assets/js/src/newsletters/types/standard.jsx

@@ -18,10 +18,10 @@ define(
 
     var NewsletterStandard = React.createClass({
       mixins: [
-        Router.Navigation
+        Router.History
       ],
       showTemplateSelection: function(newsletterId) {
-        this.transitionTo('/template/' + newsletterId);
+        this.history.pushState(null, `/template/${newsletterId}`);
       },
       componentDidMount: function() {
         // No options for this type, create a newsletter upon mounting

assets/js/src/newsletters/types/welcome.jsx

@@ -66,7 +66,7 @@ define(
 
     var NewsletterWelcome = React.createClass({
       mixins: [
-        Router.Navigation
+        Router.History
       ],
       getInitialState: function() {
         return {
@@ -121,7 +121,7 @@ define(
         }.bind(this));
       },
       showTemplateSelection: function(newsletterId) {
-        this.transitionTo('/template/' + newsletterId);
+        this.history.pushState(null, `/template/${newsletterId}`);
       },
       render: function() {
         var roleListSelection, timeNumber;