tvnamer has a direct dependency on old version of requests-cache 0.5.2.
Unfortunately, it was failing to build as it was missing setuptools.
This change adds this dependency. Along with the fixes to tvdb_api, now
tvnamer correctly builds.
tvnamer is an application and should as such never have existed under
python3Packages so move it out where it belongs.
At the same time override tvdb_api to use an older requests-cache as it
has a hard requirement on requests-cache < 0.6.
