ipv6 support

[jsn]

The module doesn't work with ipv6. I didn't try workers, but with clients, there are (at least) two issues.
Firstly, server endpoint parsing code uses hostport_tuple.split(':'), which is bad for ipv6 (since ipv6 addresses contain a lot of ':').
Secondly, what's worse, it uses an explicit AF_INET for connect(), which restricts it to IPv4 addresses. Is there a reason for that?

The following patch fixes the second issue and allows the client code to work at least when the server address is specified as a name or as a tuple of (ipv6_addr, port):

--- connection.py.old       2015-06-13 16:46:27.000000000 +0300
+++ connection.py       2015-06-15 13:41:18.976557457 +0300
@@ -94,8 +94,8 @@
     def _create_client_socket(self):
         """Creates a client side socket and subsequently binds/configures our socket options"""
         try:
-            client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-            client_socket.connect((self.gearman_host, self.gearman_port))
+            client_socket = socket.create_connection(
+                    (self.gearman_host, self.gearman_port))
         except socket.error, socket_exception:
             self.throw_exception(exception=socket_exception)