Remove bundled ez_setup, require setuptools for development

* ez_setup has not been updated in 7 years: https://github.com/pypa/setuptools/tree/bootstrap
* See pypa/setuptools#581

Author: phillbaker

HACKING.rst

@@ -231,8 +231,7 @@ RELEASE PROCEDURE
 
 1. Document the release correctly in ``README.rst``.
 
-2. Test the project build with the latest available ``setuptools`` project and
-   update the ``ez_setup.py`` ``setuptools`` installation script as needed.
+2. Test the project build with the latest available ``setuptools`` project.
 
   * Use the latest available & tested ``setuptools`` release.
   * If a new ``setuptools`` release drops support for an older Python release,

MANIFEST.in

@@ -5,7 +5,6 @@
 # tried out did not work correctly with Python 3.
 
 # Top level project files.
-include ez_setup.py
 include HACKING.rst
 include LICENSE.txt
 include TODO.txt