Fix lambda expression of "parenthesize_version" filter.
Enable py3k compatibility for "generate" command.
Fix glob and _augment_data_from_tarball():

* Calling glob with "{0}-{1}*".format(args.name, args.version)
  fails if the user has extracted the tarball in the current
  working directory: py2pack will try to open the package
  directory as a tarball. Remediate by inserting a dot
  ("{0}-{1}.*") to make sure that the opened file has at
  least some kind of filename extension.

* If the file identified with glob is neither a tarfile nor
  a zipfile, _augment_data_from_tarball() will raise an
  exception in "for name in names" because "names" is
  undefined. Fix by simply calling return if the filetype
  is not known.