add an example for pipeline

examples/pipeline.py

@@ -0,0 +1,38 @@
+import tornado
+import tornadis
+
+
+@tornado.gen.coroutine
+def pipeline_coroutine():
+    # Let's get a connected client
+    client = tornadis.Client()
+    yield client.connect()
+
+    # Let's make a pipeline object to stack commands inside
+    pipeline = tornadis.Pipeline()
+    pipeline.stack_call("SET", "foo", "bar")
+    pipeline.stack_call("GET", "foo")
+
+    # At this point, nothing is sent to redis
+
+    # Let's submit the pipeline to redis and wait for replies
+    results = yield client.call(pipeline)
+
+    # The two replies are in the results array
+    print results
+    # >>> ['OK', 'bar']
+
+    # Let's disconnect
+    client.disconnect()
+
+
+def stop_loop(future):
+    exception = future.exception()
+    if exception is not None:
+        raise(exception)
+    loop.stop()
+
+
+loop = tornado.ioloop.IOLoop.instance()
+loop.add_future(pipeline_coroutine(), stop_loop)
+loop.start()