NEO/py/storage: Ensure compression is always BOOL on the wire

Currently it can be:

- nil
- bool
- integer

In python this isn't really a problem due to '__bool__', but in Golang
we don't have this. Yes - it would be possible to make a parser in
Golang to decode all of these values as either True/False, but this is
much more complex than just adjusting python to send consistent data
types. It's also easier to describe a protocol where one parameter is
always 'bool' instead of having a parameter that is 'bool | int | NoneType'.

neo/storage/handlers/client.py

@@ -75,7 +75,7 @@ class ClientOperationHandler(BaseHandler):
                 checksum = ZERO_HASH
                 data = ''
             p = Packets.AnswerObject(oid, serial, next_serial,
-                compression, checksum, data, data_serial)
+                bool(compression), checksum, data, data_serial)
         conn.answer(p)
 
     def askStoreTransaction(self, conn, ttid, *txn_info):