Merge PR 9 (improved integration tests)

PyPy's zipimport._zip_directory_cache implementation does not support direct
item assignment, thus breaking our attempts at silently updating the cached zip
archive directory information behind the scene. As a workaround, when using
PyPy, we fall back to simply clearing the stale cached information.

--HG--
extra : amend_source : 991e30244754d8fac042da56ac4cf0ad1a0f50d5

--HG--
extra : rebase_source : beb6c57dfd500432304518b9d313d1a98e2614b9

--HG--
extra : rebase_source : 04b4807ccc7bf95d87797716f5d3488d420fa692

--HG--
rename : setuptools/script template (dev).py => setuptools/script (dev).tmpl
rename : setuptools/script template.py => setuptools/script.tmpl

Now that 2to3 is no longer run on the codebase, it's safe for the templates to be syntactically incorrect (prior to substitution).