Revert "Grab the version number from webob/version.py"

This reverts commit 01a188e0d91b664f2ddb79bad68d75f68de56d08.
Revert "Add new version.py file containing the version"

This reverts commit ae4f87979df0e35f9eb791ae0d70141a5b3b0502.
Revert "Remove pkg_resources (setuptools dependency) and import version"

This reverts commit c75ee9afaaaed4233b49c0a25a870a685a03467d.
Remove __version__ entirely