Remove Old Multi-Client Code / Refactoring (#13)

* Remove a lot of old code from render_queue regarding clients

* More code cleanup

* More code cleanup

* Move everything around

* Minor log change

lib/workers/worker_factory.py

@@ -0,0 +1,29 @@
+class RenderWorkerFactory:
+
+    @staticmethod
+    def supported_classes():
+        # to add support for any additional RenderWorker classes, import their classes and add to list here
+        from .blender_worker import BlenderRenderWorker
+        from .aerender_worker import AERenderWorker
+        from .ffmpeg_worker import FFMPEGRenderWorker
+        classes = [BlenderRenderWorker, AERenderWorker, FFMPEGRenderWorker]
+        return classes
+
+    @staticmethod
+    def create_worker(renderer, input_path, output_path, priority=2, args=None, owner=None,
+                      client=None, name=None):
+        worker_class = RenderWorkerFactory.class_for_name(renderer)
+        return worker_class(input_path=input_path, output_path=output_path, args=args, priority=priority, owner=owner,
+                            client=client, name=name)
+
+    @staticmethod
+    def supported_renderers():
+        return [x.engine.name() for x in RenderWorkerFactory.supported_classes()]
+
+    @staticmethod
+    def class_for_name(name):
+        name = name.lower()
+        for render_class in RenderWorkerFactory.supported_classes():
+            if render_class.engine.name() == name:
+                return render_class
+        raise LookupError(f'Cannot find class for name: {name}')