added support for module value sources + pyflake cleanup

This revision adds the use of python modules as value sources.  The name of a module in a package can now be used instead of a configuration file:

    .../config/commonconfig.py:
        HBaseHost = 'localhost'
        HBasePort = 9090

    .../some/dotted/module.py:
        from config.commonconfig import HBaseHost as hbase_host
        from config.commonconfig improt HBasePort as hbase_port
        stderr_logging_level = 30

    $ someconfigman_app --admin.conf=some.dotted.module --help
       someconfigman_app 1.0
          --hbase_port
             the port that HBase needs to connect to (default:9090)
          --hbase_host
            the host on which HBase is found (default:localhost)
          --stderr_logging_level
            the logging level for stderr (default: 30)