setup.py: add setuptools to install_requires

Closes: https://github.com/Pylons/pastedeploy/issues/28

* remove pytest-runner

`pytest-runner` describes itself as deprecated in its own package
description, referring to
https://github.com/pypa/setuptools/issues/1684.  Using it in
`setup_requires` means that any other package that depends on
PasteDeploy has to install `pytest-runner` too, which is fairly
heavyweight and unnecessary.  (I ran into this when trying to update
Launchpad to a less ancient version of PasteDeploy.)

This does mean that `python setup.py test` no longer works, but,
according to the setuptools issue above, that's deprecated anyway.
PasteDeploy already has `tox` configuration that works well.

* Include license.txt in PyPi release

* Include tests in PyPi release

Mini-release to cover release faults and small docs cleanups.

* Prepare a 2.0.0 release

Update version in setup.py
Add changes to news.rst
Add build artifacts to .gitignore

The rationale for using a 2.0.0 version number is to make a
rather heavy-handed signal about the change in project
hosting and maintenance.

* Fixup text and links in 2.0.0 news

Better linking and more complete text