Code review comment for lp:~jameinel/launchpadlib/win32

I found that there is another failure condition, which was pretty easy to fix.

So this patch does:

1) Change the symlink bootstrap.py into a trivial boostrap.py script that just thunks into the real _bootstrap/bootstrap.py
2) Change a trap for:
  if isinstance(cache, str):
to
  if isinstance(cache, basestring):

This is because "tempfile.mkdtemp()" on win32 returns a Unicode string. (Since the underlying filesystem is UTF-16 it makes sense to do so.)