Adoption of debtcollector as a new library for oslo-incubator

Currently https://review.openstack.org/#/c/140119/ is proposed to move into oslo.utils; but this seemed to be better on its own as a library that can provide these common types of patterns. Therefore this is being created and https://launchpad.net/debtcollector is created to represent this new library going forward.

Enforce cinder states using a `enforcer` model for Cinder

Not related to arnold schwarzenegger... Also note, not related to clint eastwood in http://en.wikipedia.org/wiki/The_Enforcer_%281976_film%29 See: https://review.openstack.org/#/c/95037/

Endpoint should use entrypoints for taskflow

Instead (or in addition to) of scanning classes/modules for tasks when a worker program starts up we should also make it possible to use/provide entrypoints (or a list of entrypoints) and then interact with stevedore to find and load the tasks provided by these entrypoints.

Redis backed jobboard and workers for taskflow

Redis backed jobboard and workers

Logbook objects, not collections for taskflow

It is proposed to stop treating logbook object as collection of smaller objects: LogBook and FlowDetails should be made simple data-transfer objects, not containers for FlowDetails and AtomDetails respectively. Corresponding API should be moved to backends.