[PATCH] Avoid importing unused libraries in tests scripts

Hello,

This is a follow-up for r22444. This time it fixes the issues in scripts
under tests/cmdline/svntest directory. Please find attached the patch
for review.

[[
Avoid importing unused python libraries in the black box regression
tests.

[ in subversion/tests/cmdline/svntest ]
* testcase.py
  Do not import unused libraries.
  (TestCase.check_description): Use the string itself when invoking the
  lower() function.

* tree.py
  Do not import unused libraries.
  (create_from_path, dump_tree): Use the string itself when invoking the
  replace() function.
  (get_props): Use the string itself when invoking the strip() function.

* actions.py
  Do not import unused libraries.
  (setup_pristine_repository, run_and_verify_commit): Use the string
  itself when invoking strip() function.

* main.py
  Do not import unused libraries.
  Use the string itself when invoking replace() function.
  (Sandbox._set_name, run_tests): Use the string itself when invoking
  replace() function.

Patch by: bhuvan
]]

-- 
Regards,
Bhuvaneswaran