subtests/docker_cli/attach: Pylint fixups

*  Add methods for matching expected
   or unexpected configuration strings
   against docker command output.

*  Add method to assemble list of
   sub-subtest specific parameters
   to output-matching methods.

*  Make postprocess method generic,
   by taking result of assembling
   parameter lists, and passing them
   to matching methods.

*  Make sig_proxy sub-subtests postprocess
   generic by using new specialized
   check_containers() method.

Signed-off-by: Chris Evich <cevich@redhat.com>
subtests...psa: Improved test reliability

*  Fixed: Test incorrectly called get_container_list()
   instead of list_containers()

*  Fixed:  Test would break if image needed to be downloade.

*  Fixed: Test did not use common name generation.

*  Fixed: Inaccurate list-size comparison condition.  Check
   existance of container id instead.

Signed-off-by: Chris Evich <cevich@redhat.com>
subtests...run_volumes: Fix bugs, improve logging.

*  It was difficult to see what went wrong when running
   these tests.  Added some helpful messages.

*  Switched config from using old string.template to
   new string format /w dictionary subs.

*  Fixed problem with not checking test paths exist on
   host, and are directory.

Signed-off-by: Chris Evich <cevich@redhat.com>
gitignore: Only ignore ini files in config_custom

Signed-off-by: Chris Evich <cevich@redhat.com>
config: noise reduction + doc update

*  Excessive complaining on every test if
   unknown, non-ini file found in a config dir.

*  Updated config_custom README file.

Signed-off-by: Chris Evich <cevich@redhat.com>
subtests...start: long_term_app unused import

Signed-off-by: Chris Evich <cevich@redhat.com>
run_pylint: Allow checking specific files

Signed-off-by: Chris Evich <cevich@redhat.com>
dockertest.containers: Add attribute for remove method

Signed-off-by: Chris Evich <cevich@redhat.com>
subtests...rm: Improve logging & reliability

Signed-off-by: Chris Evich <cevich@redhat.com>
dockertest.dockercmd:  Improve debugging & cache results

*  Previously there was no way to access the cmdresult object
   after execute() or wait() unless you stored it.  Added
   a cache attribute to DockerCmdBase that stores the
   cmdresult from the most recent execute() call.

*  AsyncDockerCmd does not return a useful cmdresult object
   unless you call wait() first.  Added new method
   update_result() which forces an update of stdout/stderr
   content in the cached cmdresult object.

*  Setup all DockerCmd classes to log the current
   cached cmdresult during string conversion.

Signed-off-by: Chris Evich <cevich@redhat.com>
subtests...psa: Improve logging & reliability

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