Hooks for pylint, astroid and accompanying fixes.

Add: Hooks for pylint and its dependency, astroid.
     Optional subdir parameter to hookutils.collect_data_files,
       .collect_submodules to support pattern of run-time imports in a directory
       lacking __init__.py.
     Tests for pylint.
Fix: Pylint prints out lots of output, which isn't ready by runtests.py. Be sure
       to read all stdout when the process finishes.
Please add the copyright header as it is in file test_pylint.py