msgpack: Add 1.0.0 version support

Since msgpack 1.0.0 was released Unpacker does not have
strict_map_key param and it is True by default now.

It makes the Connector fail with an error:
`ValueError: int is not allowed for map key`

To solve this issue the __init__ method of the Response
object was refactored and the strict_map_key param is
added for versions less than 1.0.0

Fixes #155

Author: artembo

Diff for: tarantool/response.py

@@ -50,16 +50,19 @@ def __init__(self, conn, response):
         # created in the __new__().
         # super(Response, self).__init__()
 
+        kwargs = dict(use_list=True)
+        if msgpack.version >= (1, 0, 0):
+            # XXX: Explain why it is necessary.
+            kwargs['strict_map_key'] = False
         if msgpack.version >= (0, 5, 2) and conn.encoding == 'utf-8':
             # Get rid of the following warning.
             # > PendingDeprecationWarning: encoding is deprecated,
             # > Use raw=False instead.
-            unpacker = msgpack.Unpacker(use_list=True, raw=False)
+            kwargs['raw'] = False
         elif conn.encoding is not None:
-            unpacker = msgpack.Unpacker(use_list=True, encoding=conn.encoding)
-        else:
-            unpacker = msgpack.Unpacker(use_list=True)
+            kwargs['encoding'] = conn.encoding
 
+        unpacker = msgpack.Unpacker(**kwargs)
         unpacker.feed(response)
         header = unpacker.unpack()