being run using a Python version different from the minimum
version the webkitpy package was meant to support.

Reviewed by Adam Barth.

https://bugs.webkit.org/show_bug.cgi?id=35788

Warning developers if their Python version is too low will help
them understand why test-webkitpy is failing.  Secondly, warning
developers if their Python version is higher than the minimum will
help them understand that their changes may not be okay for the
minimum supported version, even if test-webkitpy is passing.

* Scripts/test-webkitpy:
  - Moved the "from ..._unittest import *" lines to the new
    file Scripts/webkitpy/unittests.py.  This will allow the
    version-check warning to be displayed even if an error occurs
    while interpreting (i.e. importing) the unit test code.
  - Added configure_logging() to configur logging for test-webkitpy.
  - Added an init() method to configure logging and check the
    current Python version.

* Scripts/webkitpy/init/unittests.py: Added.
  - Added a file to import all unit test modules in the
    webkitpy.init package.

* Scripts/webkitpy/init/versioning.py: Added.
  - Added a _MINIMUM_SUPPORTED_PYTHON_VERSION variable and set
    it equal to 2.5.
  - Added a compare_version() method to compare the current Python
    version against a target version.
  - Added a check_version() method to check the current Python
    version against the current minimum supported version, and to
    log a warning message if the check fails.

* Scripts/webkitpy/init/versioning_unittest.py: Added.
  - Added unit tests for the functions in versioning.py.

* Scripts/webkitpy/style/unittests.py:
  - Fixed/updated a code comment.

* Scripts/webkitpy/unittests.py: Added.
  - Moved the "from ..._unittest import *" lines from test-webkitpy.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@55970 268f45cc-cd09-0410-ab3c-d52691b4dbfc