Move halcyon registration to model boot

Attempt to fix issue where service provider looks at system_preferences database table that doesn't exist yet as part of the boot() method
Fixes #1897

modules/cms/ServiceProvider.php

@@ -48,7 +48,6 @@ class ServiceProvider extends ModuleServiceProvider
     {
         parent::boot('cms');
 
-        $this->bootDefaultTheme();
         $this->bootMenuItemEvents();
         $this->bootRichEditorEvents();
     }
@@ -285,21 +284,4 @@ class ServiceProvider extends ModuleServiceProvider
             }
         });
     }
-
-    /**
-     * Boot the default theme.
-     */
-    protected function bootDefaultTheme()
-    {
-        $resolver = App::make('halcyon');
-        if ($resolver->getDefaultDatasource()) {
-            return;
-        }
-
-        $defaultTheme = App::runningInBackend()
-            ? CmsTheme::getEditThemeCode()
-            : CmsTheme::getActiveThemeCode();
-
-        $resolver->setDefaultDatasource($defaultTheme);
-    }
 }

modules/cms/classes/CmsObject.php

@@ -1,5 +1,6 @@
 <?php namespace Cms\Classes;
 
+use App;
 use Lang;
 use Config;
 use October\Rain\Halcyon\Model as HalcyonModel;
@@ -62,6 +63,36 @@ class CmsObject extends HalcyonModel implements CmsObjectContract
         parent::__construct($attributes);
     }
 
+    /**
+     * The "booting" method of the model.
+     * @return void
+     */
+    protected static function boot()
+    {
+        parent::boot();
+        static::bootDefaultTheme();
+    }
+
+    /**
+     * Boot all of the bootable traits on the model.
+     * @return void
+     */
+    protected static function bootDefaultTheme()
+    {
+        $resolver = static::getDatasourceResolver();
+        if ($resolver->getDefaultDatasource()) {
+            return;
+        }
+
+        $defaultTheme = App::runningInBackend()
+            ? Theme::getEditThemeCode()
+            : Theme::getActiveThemeCode();
+
+        Theme::load($defaultTheme);
+
+        $resolver->setDefaultDatasource($defaultTheme);
+    }
+
     /**
      * Loads the object from a file.
      * This method is used in the CMS back-end. It doesn't use any caching.

modules/system/ServiceProvider.php

@@ -97,9 +97,11 @@ class ServiceProvider extends ModuleServiceProvider
         App::singleton('backend.helper', function () {
             return new \Backend\Helpers\Backend;
         });
+
         App::singleton('backend.menu', function () {
             return \Backend\Classes\NavigationManager::instance();
         });
+
         App::singleton('backend.auth', function () {
             return \Backend\Classes\AuthManager::instance();
         });