Port to argparse based cfg

Implements blueprint argparse-based-cfg

Sync the following changes from oslo-incubator:

479f19c Add deprecated --logdir common opt
27b2ff4 Add deprecated --logfile common opt.
9b81289 Allow nova and others to override some logging defaults
3557d84 Fix ListOpt to trim whitespace
01ab910 Fix set_default() with boolean CLI options
af18eaa Improve cfg's argparse sub-parsers support
f21e1d9 Fix regression with cfg CLI arguments
ceb4aa7 Fix broken --help with CommonConfigOpts
5e9503b Hide the GroupAttr conf and group attributes
b6d24bb updating sphinx documentation
403509e Don't reference argparse._StoreAction
e17deb8 Fix minor coding style issue
0c29e1d Remove ConfigCliParser class
5b9cb41 Add support for positional arguments
dbc72a6 Use stock argparse behaviour for optional args
768a147 Use stock argparse --usage behaviour
ac180b9 Use stock argparse --version behaviour
0787e38 Remove add_option() method
5afead0 Completely remove cfg's disable_interspersed_args()
5f564b2 argparse support for cfg
d7b6397 Add a missing comma in a docstring.
aca1805 cfg: fix required if option has a dash

Note: various utilities/services with command line parameters needed to be
updated due to the changes mentioned above. The downside is that these are
not backward compatible. Unknown arguments are no ignored. Only bound
arguments will be treated.

Thanks to Mark McLoughlin for migration cli code changes.

Change-Id: Ia776e78cc55f4ed33ace5efa8d726b70e3fa4131
Merge "Port to argparse based cfg"