Make standalone registration more accessible

Add buttons for switching between the linking flow and the standalone
registration flow. The button and standalone registration are only
availble in a development environment.

// FREEBIE

background.html

@@ -669,6 +669,9 @@
           <p>{{ installAndroidInstructions }}</p>
         </div>
         <div class='nav'>
+          {{ #development }}
+            <div> <a class='button openStandalone'>Standalone</a> </div>
+          {{ /development }}
           <span class='dot step1'></span>
           <span class='dot step2'></span>
           <span class='dot step3 selected'></span>
@@ -752,6 +755,7 @@
             <input class='form-control' type="text" pattern="\s*[0-9]{3}-?[0-9]{3}\s*" title="Enter your 6-digit verification code. If you did not receive a code, click Call or Send SMS to request a new one" id="code" placeholder="Verification Code" autocomplete='off'>
             <button id="verifyCode" class="btn btn-info" data-loading-text="Please wait...">Register</button>
             <div id='error' class='collapse'></div>
+            <div> <a class='button openInstaller'>Link to phone</a> </div>
           </form>
           <div id=status></div>
         </div>

js/views/app_view.js

@@ -9,6 +9,8 @@
           this.installView = null;
         },
         events: {
+            'click .openInstaller': 'openInstaller',
+            'click .openStandalone': 'openStandalone',
             'openInstaller': 'openInstaller',
             'openInbox': 'openInbox',
         },

js/views/install_view.js

@@ -26,6 +26,7 @@
                 installFinalButton: i18n('installFinalButton'),
                 installTooManyDevices: i18n('installTooManyDevices'),
                 ok: i18n('ok'),
+                development: window.config.environment === 'development'
             };
         },
         initialize: function(options) {