Add Support for Timeout Parameter

[jthigpen]

We added support for a timeout parameter to the wordpress library as detailed in http://stackoverflow.com/questions/372365/set-timeout-for-xmlrpclib-serverproxy.

It seems like a good idea to allow people to specify a timeout when interacting with third party services over a network. We needed this for our project and thought we would offer back the modifications we made.

[maxcutler]

In version 2.3 I've exposed a transport parameter that you can pass with your custom transports. I'm not sure it makes sense to bundle particular transports in the library, but you should feel free to put it in a separate package and upload it to PyPI for easy sharing and consumption.