Fixes #7

* added a synchronous cluster simulation

* added a test for the sync function

* moved signing into its own module

* refactored imports to solve circular import problems stemming from the task module pretending to be a cluster

* added documentation for the new sync option

django_q/tests/test_cluster.py

@@ -32,6 +32,10 @@ def r():
 def test_redis_connection(r):
     assert r.ping() is True
 
+@pytest.mark.django_db
+def test_sync(r):
+    task = async('django_q.tests.tasks.count_letters', DEFAULT_WORDLIST, redis=r, sync=True)
+    assert result(task) == 1506
 
 @pytest.mark.django_db
 def test_cluster_initial(r):