fix(bootstrap): Logging CLI options don't work

In the current implementation, Bootstrap creates the config option
inside its initializer. That means that common options such as
those registered by openstack.common.log, are not registered.

This patch modifies the Bootstrap initializer to take a config
instance from the caller, rather than trying to build one
itself. This does two things for us:

1. Avoids "magic" marconi configuration; the caller has full
   control and visibility into how marconi is configured.
2. Allows for passing in the global CONF object from the
   marconi-server command and the reference WSGI app module
   so that common options registered by oslo modules on the
   global CONF instance are picked up.

Hopefully openstack.common.log will be modified at some point
so that it isn't tightly coupled with cfg.CONF.

Implements: blueprint remove-global-config
Change-Id: Ibb6638f99ca2ce4a2a6025f6cd41939bb30fa85a
Merge "fix(bootstrap): Logging CLI options don't work"