merge lp:~gary/zc.buildout/betafix8.  merges trunk and simplifies the pattern for using newer versions of buildout, per review.

By default, Buildout and the bootstrap script now prefer final versions of Buildout, recipes, and extensions.

fix the more troublesome problems with Python 2.7.  Tests still fail after these changes, but only for trivial output-ordering issues.

fix virtualenv interaction by identfying broken virtualenv characteristic and reverting to previous behavior in that case.

move the new bootstrap aside to let virtualenv users that have packages linked to bootstrap in trunk stay happy.

merge lp:~gary/zc.buildout/python-support (also available as svn+ssh://svn.zope.org/repos/main/zc.buildout/branches/gary-launchpad).  This adds support for system Pythons, as well as other changes, such as improved Distribute support and some cleanups.

Warning when a script name passed in 'scripts' argument of easy_install.scripts
is not defined in an entry point.

fixes for bootstrap and a system Python; changes based on learning what would be necessary to be able to develop buildout with a system Python (zc.recipe.testing would also need to use sitepackage_safe_scripts)