Re-structured the app code to be feature based rather than code type based

Author: ssddanbrown

app/Activity.php app/Actions/Activity.php

@@ -1,6 +1,9 @@
 <?php
 
-namespace BookStack;
+namespace BookStack\Actions;
+
+use BookStack\Auth\User;
+use BookStack\Model;
 
 /**
  * @property string  key

app/Services/ActivityService.php app/Actions/ActivityService.php

@@ -1,7 +1,8 @@
-<?php namespace BookStack\Services;
+<?php namespace BookStack\Actions;
 
-use BookStack\Activity;
-use BookStack\Entity;
+use BookStack\Actions\Activity;
+use BookStack\Auth\Permissions\PermissionService;
+use BookStack\Entities\Entity;
 use Session;
 
 class ActivityService
@@ -12,7 +13,7 @@ class ActivityService
 
     /**
      * ActivityService constructor.
-     * @param Activity $activity
+     * @param \BookStack\Actions\Activity $activity
      * @param PermissionService $permissionService
      */
     public function __construct(Activity $activity, PermissionService $permissionService)