Adds timeout and reincarnation test

Also found a bug because of this.

django_q/tests/tasks.py

@@ -1,4 +1,7 @@
 # simple countdown, returns nothing
+from time import sleep
+
+
 def countdown(n):
     while n > 0:
         n -= 1
@@ -23,6 +26,11 @@ def word_multiply(x, word=''):
     return len(word) * x
 
 
+def count_forever():
+    while True:
+        sleep(0.5)
+
+
 def get_task_name(task):
     return task.name