Teach the cmdline tests to use pre-cooked greek repositories.
One or two tests currently fail in this mode due to making
too many assumptions about the behaviour of the test harness.

* subversion/tests/cmdline/svntest/main.py
  (_unpack_precooked_repos): Helper function for unzipping
   the pre-cooked repository packages.
  (unpack_greek_repos): New; unpacks a pre-cooked greek repos.
  (create_repos): Use _unpack_precooked_repos.

* subversion/tests/cmdline/svntest/actions.py
  (setup_pristine_greek_repository,
   guarantee_greek_repository): Use the new main.unpack_greek_repos
   when in pre-cooked mode.

* subversion/tests/templates/greek-fsfs-v4.zip,
  subversion/tests/templates/greek-fsfs-v6.zip: New;
   pre-cooked repositories with the greek tree included.
* subversion/tests/templates/greek.dump: New;
   greek tree dump file for creating new pre-cooked repositories.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1619764 13f79535-47bb-0310-9956-ffa450edef68