Convert to using ClientManager and OpenStackShell from osc-lib.
* Change all internal uses of ClientManager private attributes that are
now public in osc-lib's ClientManager. Leave back-compat copies in
place in OSC's clientManager so we don't break plugins.
* Put some work-arounds in place for changes in osc-lib that we need until
a new release makes it through the g-r and u-c change process.
* Add a test for Unicode decoding of argv in shell.main() to parallel
the one in osc-lib.
Change-Id: I85289740d4ca081f2aca8c9b40ec422ad25d302c
6a15f90dae