Implement backward compatiblility

Create a class `FauxFactory`. Provide it with an identical set of public
class methods, and make them call the equivalent new-style functions. Also
provide a `codify` function that wraps the new `_make_unicode` function.

Provide a basic set of sanity tests for these wrappers.

Do not alter the module-wide variable `__all__`. This prevents the compatiblity
code from showing up in Sphinx-generated documentation or being imported by
`from fauxfactory import *`.