Refactor: DistributedJobManager with pub/sub status change notifications (#25)

* Add pubsub to render_queue and base_worker

* Refactor: Convert ZeroconfServer to Singleton with Class Methods

* New API for subjob servers to notify parent job servers of status changes

* Refactor: Move all subjob related methods to distributed_job_manager.py

* Rewrite for wait_for_subjobs

* Fix: DistributedJobManager.find_available_servers() takes 1 positional argument but 3 were given

* DistributedJobManager should now notify / be notified abotu background job changes

* Fix the make_ready api. Change children keyname to be id@hostname so it can be unique

* Fixes

* Image sequence to movie needs to find the actual start frame

* Fix: subjob_status_change did not return a valid response

* Fix client renderer selection

* Small fix for subjob status checking

* Fix issue with divide_frames_equally

* Fix issue where downloads were not occurring

* Fix issue where old status was being reported

* Add docstrings and code cleanup

lib/server/server_proxy.py

@@ -10,9 +10,9 @@ from requests_toolbelt.multipart import MultipartEncoder, MultipartEncoderMonito
 
 status_colors = {RenderStatus.ERROR: "red", RenderStatus.CANCELLED: 'orange1', RenderStatus.COMPLETED: 'green',
                  RenderStatus.NOT_STARTED: "yellow", RenderStatus.SCHEDULED: 'purple',
-                 RenderStatus.RUNNING: 'cyan'}
+                 RenderStatus.RUNNING: 'cyan', RenderStatus.WAITING_FOR_SUBJOBS: 'blue'}
 
-categories = [RenderStatus.RUNNING, RenderStatus.WAITING, RenderStatus.ERROR, RenderStatus.NOT_STARTED, RenderStatus.SCHEDULED,
+categories = [RenderStatus.RUNNING, RenderStatus.WAITING_FOR_SUBJOBS, RenderStatus.ERROR, RenderStatus.NOT_STARTED, RenderStatus.SCHEDULED,
               RenderStatus.COMPLETED, RenderStatus.CANCELLED, RenderStatus.UNDEFINED]
 
 logger = logging.getLogger()
@@ -114,6 +114,10 @@ class RenderServerProxy:
     def get_status(self):
         return self.request_data('status')
 
+    def notify_parent_of_status_change(self, parent_id, subjob):
+        return requests.post(f'http://{self.hostname}:{self.port}/api/job/{parent_id}/notify_parent_of_status_change',
+                             json=subjob.json())
+
     def post_job_to_server(self, file_path, job_list, callback=None):
 
         # bypass uploading file if posting to localhost