dependency when a distribution lacks a ``dependency_links`` setting.

* Made ``zip-safe`` and ``not-zip-safe`` flag files contain a single byte,
  so as to play better with packaging tools that complain about zero-length
  files.

* Made ``setup.py develop`` respect the ``--no-deps`` option, which it
  previously was ignoring.

(bug fixes backported from trunk)

--HG--
branch : setuptools-0.6
extra : convert_revision : svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/sandbox/branches/setuptools-0.6%4050659