Increase connector buffer size for receiving

When receiving 1 byte, benchmarking shows no visible difference with values
between 4096 and 65536 for the buffer size. With higher values, it becomes
significantly slower.

On the other side, a 64k buffer is faster with bigger packets.
Time to run testBasicStore with MySQL:

            4096        65536
    real    0m51.115s   0m21.592s
    user    0m41.857s   0m13.540s
    sys     0m8.700s    0m2.687s

neo/lib/connector.py

@@ -145,7 +145,7 @@ class SocketConnector(object):
 
     def receive(self, read_buf):
         try:
-            data = self.socket.recv(4096)
+            data = self.socket.recv(65536)
         except socket.error, e:
             self._error('recv', e)
         if data:
@@ -155,6 +155,7 @@ class SocketConnector(object):
         raise ConnectorException
 
     def send(self):
+        # XXX: unefficient for big packets
         msg = ''.join(self.queued)
         if msg:
             try: