Add tests.test_task with basic test for activity registration

tests/test_task.py

@@ -0,0 +1,24 @@
+from simpleflow import activity
+
+
+@activity.with_attributes(task_list='test')
+def increment(x):
+    return x + 1
+
+
+@activity.with_attributes(task_list='test')
+def double(x):
+    return x * 2
+
+
+@activity.with_attributes(task_list='test')
+def square(x):
+    return x * x
+
+
+print increment.name
+
+def test_task_register():
+    from simpleflow import task
+
+    assert task.registry['test'] == [increment, double, square]