This commit intentionally introduces a number of important API
breakages. Specifically, the jenkins_jobs.cmd module has been pared
down to some of its most difficult-to-refactor elements.
* Create jenkins_jobs.cli.entry.JenkinsJobs class to organize command
line parsing and execution.
* Remove references to ConfigParser object in test code, hidden as an
implementation detail of JenkinsJobs command line parsing. This will
be necessary in the next stage of JJB 2.0 code which will be to
create a JJBConfig object that handles logic and presentation of
configuration from various sources--defaults, command line
arguments, configuration file, and maybe environment variables in
the future.
* Remove references to Namespace object produced by argparse module.
Required rewrite of multipath & recursive path tests with a new
MatchesDir testtools Matcher class that validates the expected
output for a run of JJB against a given set of yamldirs with the
specified command line arguments.
* Use stevedore to dynamically load subcommand parsers.
* Move configuration loading/testing to its own test file. Also fix
the global vs home directory JJB config file test.
Change-Id: If62280418ba7319c313033ab387af4284237747e