Modification to allow multiple pagination objects on same page

[pipermerriam]

Currently, the page parameter produces conflicts when you have multiple pagination objects on the same page.

This patch provides an extra keyword argument to the Page object initialization and the paginator.page() call allowing you to customize the name of the query parameter used for generating the querystring within the page object.

All fo the tests pass, and this should not cause any backwards compatibility problems since the new argument is optional.