Feature: split mako from pyramid

This starts the process of splitting the Mako templating system from pyramid itself. I have grabbed the latest version of the mako_templating.py from pyramid and copied it over.

This also makes sure to grab the latest tests and the required fixtures and makes them available.

Last but not least it makes the `includeme()` function an entrypoint for pkg_resources, which means that in pyramid's `setUp()` for testing we can iterate over the entry points and if the mako templating system package is installed for pyramid (this package to be more specific) it will be automatically picked up and used.