Merge pull request #98 from chripede/master

RedisDummyCache

redis_cache/__init__.py

 from redis_cache.backends.single import RedisCache
 from redis_cache.backends.multiple import ShardedRedisCache
+from redis_cache.backends.dummy import RedisDummyCache

redis_cache/backends/dummy.py

+from django.core.cache.backends.dummy import DummyCache
+
+
+class RedisDummyCache(DummyCache):
+    def ttl(self, key):
+        return 0
+
+    def delete_pattern(self, pattern, version=None):
+        return None
+
+    def get_or_set(self, key, func, timeout=None):
+        if not callable(func):
+            raise Exception("Must pass in a callable")
+
+        return func()
+
+    def reinsert_keys(self):
+        return None
+
+    def persist(self, key):
+        return True
+
+    def expire(self, key, timeout):
+        return True