Adds optional task_name argument

Makes it possible to name the task yourself.

django_q/tasks.py

@@ -24,7 +24,7 @@ def async(func, *args, **kwargs):
     tag = uuid()
     # build the task package
     task = {'id': tag[1],
-            'name': tag[0],
+            'name': q_options.pop('task_name', None) or tag[0],
             'func': func,
             'args': args}
     # push optionals

docs/tasks.rst

@@ -69,6 +69,11 @@ broker
 """"""
 A broker instance, in case you want to control your own connections.
 
+task_name
+"""""""""
+
+Optionally overwrites the auto-generated task name.
+
 q_options
 """""""""
 None of the option keywords get passed on to the task function.