Docker: Version 0.1.1 updates

*  Support custom and/or private test modules and/or configurations.
   Otherwise modifying the default configs. will make version control
   grumpy.  Anything (includeing replacement defaults) defined inside
   the new config_custom directory tree will override content from the
   config_defaults (formerly config.d) tree.

*  Updated .gitignore file to ignore all files in config_custom
   subdirectory.

*  Subtests now support optionally setting the # of test iterations from
   their config section with the 'iterations' key.  If not present,
   it defaults to the class-attribute value.

*  Subtests and SubSubtests automatically log their configuration
   settings into the results/.../keyval file (including defaults).
   They will log a warning if no configuration section
   is found.  In this case, their config attribute is
   a copy of the defaults.

*  Added additional comments in various places, further clarifing
   decisions.  Updated documentation to version 0.1.1 reflecting
   all changes.

*  Added dockercmd module with classes to make running docker commands
   within subtests easier. Added unittests for dockercmd module.  Updated
   all bundled subtests to use dockercmd where possible

*  Added simple run_pylint.sh shell-script to run pylint across all python
   modules and tests.  Does not yet properly handle autotest deps. Will
   likely be replaced by inspektor.

Signed-off-by: Chris Evich <cevich@redhat.com>