Adds SoftLayer Message Queue functionality

This pull request is aimed at adding SoftLayer Message Queue compatibility to Kombu.

Product:
 - http://www.softlayer.com/services/additional/message-queue
API Reference:
 - http://sldn.softlayer.com/reference/messagequeueapi
Required Python Module:
 - https://github.com/softlayer/softlayer-message-queue-python
 - http://pypi.python.org/pypi/softlayer_messaging