Refactor Flarum\Web and Flarum\Admin

- In order to be consistent with the Ember/LESS naming scheme, renamed
Flarum\Web to Flarum\Forum.
- Moved common classes into Flarum\Support so that Flarum\Admin doesn’t
depend on Flarum\Forum. Also moved Actor into Flarum\Support as it
doesn’t belong in the domain.

src/Support/Action.php

@@ -0,0 +1,21 @@
+<?php namespace Flarum\Support;
+
+use Illuminate\Http\Request;
+use Illuminate\Contracts\Bus\Dispatcher;
+
+abstract class Action
+{
+    abstract public function handle(Request $request, $routeParams = []);
+
+    public function __construct(Actor $actor, Dispatcher $bus)
+    {
+        $this->actor = $actor;
+        $this->bus = $bus;
+    }
+
+    protected function callAction($class, $params = [])
+    {
+        $action = app($class);
+        return $action->call($params);
+    }
+}