Draft: Extract common packages from orchestrator into a common module.

See #126.

The orchestrator module includes many common packages that are imported by other modules, esp. placement/action controllers. These include: db, contextdb, auth, config and logutils. A controller, even if it is a 3rd party controller, needs to import the orchestrator module as a whole to get these specific dependencies.

The situation is worsened by the fact that the orchestrator itself depends on clm, rsync and monitor. This forces 3rd party modules to import far more than necessary. This can lead to or exacerbate version/package conflicts.

Signed-off-by: Sundar Nadathur