gnu: python-pip: fix inputs.

* gnu/packages/python.scm (python-pip): [inputs] change to
  [native-inputs].

gnu: python2-ipython: fix inputs.

* gnu/packages/python.scm (python2-ipython): [inputs] change to
  [native-inputs].

gnu: python-betamax: fix inputs.

* gnu/packages/python.scm (python-betamax): [inputs] change to
  [propagated-inputs].

gnu: python-scikit-learn: Remove useless property "python2-variant".

The Python 2 packages does not change the definition, thus the
propery is useless.

* gnu/packages/python.scm (python-scikit-learn): [properties]:
  Remove  "python2-variant". (python2-scikit-learn): Remove
  now needless "strip-python2-variant".

gnu: python-tables: Remove python byte-code files from source.

* gnu/packages/python.scm (python-tables)[source]: Add snippet.

gnu: python-flake8-2.2.4: Remove python byte-code files from source.

* gnu/packages/python.scm (python-flake8-2.2.4)[source]: Add snippet.

gnu: python-flake8: Remove python byte-code files from source.

* gnu/packages/python.scm (python-flake8)[source]: Add snippet.

gnu: python-testlib: Remove useless self-defined phase "unpack".

Unzipping is now done by standard-phase "unpack" automatically.

* gnu/packages/python.scm (python-testlib, python2-testlib)[phases] No longer
  replace "unpack".

gnu: python-sphinxcontrib-newsfeed: Remove needless input.

* gnu/packages/python.scm (python-sphinxcontrib-newsfeed) [propagated-inputs]:
  Remove python-docutils, already porpagated by python-sphinx.

gnu: python-nautilus: Correct inputs

* gnu/packages/python.scm(python-nautilus, python2-nautilus):
  [propagated-inputs] remove python-graphql-core, python-graphql-relay,
  python-requests: not listed and already propagated by others. Remove
  pycparser: not listed, not used in source. Move python-nose2 to
  [native-inputs] (used for tests only).

gnu: python-freezegun: Correct input.

* u/packages/python.scm(python-freezegun)[native-inputs] move
  python-dateutils-2 to [propagated-inputs].

gnu: python-consul: Correct inputs.

* gnu/packages/python.scm(python-consul)[native-inuts] move python-requests
  and python-six to [propagated-inputs].

gnu: python-prompt-toolkit: Correct inputs

* gnu/packages/python.scm(python-prompt-toolkit)[native-inputs] move
  python-six to [propagated-inputs]. Remove now empty [native-inputs].

gnu: python-responses: Correct inputs

* gnu/packages/python.scm(python-responses)[native-inputs] move python-cookies
  to [propagated-inputs]

gnu: python-sphinxcontrib-programoutput: Remove needless input.

This is an indirect requirement and propagated by python-sphinx already.

* gnu/packages/python.scm(python-sphinxcontrib-programoutput)
  [propagated-inputs]: Remove python-docutils.

gnu: python-sphinx-repoze-autointerface: Remove needless input.

This is an indirect requirement and propagated by python-sphinx already.

* gnu/packages/python.scm(python-sphinx-repoze-autointerface)
  [propagated-inputs]: Remove python-docutils.

gnu: python-celery: Remove needless inputs.

These are indirect requirements and propagated by python-kombu.

* gnu/packages/python.scm(python-celery)[propagated-inputs] Remove python-amqp
  and python-anyjson.

gnu: Remove some outdated comments.

These comments were about setuptools used at runtime for pkg_resources.

* gnu/packages/python.scm: Remove some outdated comments.

gnu: python-tox: Update FIXME comments.

* gnu/packages/python.scm(python-tox)[arguments]: Update FIXME
  comment. [inputs]: Add FIXME comment.

gnu: python-urllib3: update comment.

* gnu/packages/python.scm(python-urllib3)[propagated-inputs]: Update comment.