This commit adds support for failing deployments based on a timeout
parameter defined in the spec. If there is no progress for the amount
of time defined as progressDeadlineSeconds then the deployment will be
marked as failed by adding a condition with a ProgressDeadlineExceeded
reason in it. Progress in the context of a deployment means the creation
or adoption of a new replica set, scaling up new pods, and scaling down
old pods.
* Estimate available pods for a deployment by using minReadySeconds on
the replica set.
* Stop requeueing deployments on pod events, superseded by following the
replica set status.
* Cleanup redundant deployment utilities
* rolling.go (has all the logic for rolling deployments)
* recreate.go (has all the logic for recreate deployments)
* sync.go (has all the logic for getting and scaling replica sets)
* rollback.go (has all the logic for rolling back a deployment)
* util.go (contains all the utilities used throughout the controller)
Leave back at deployment_controller.go all the necessary bits for
creating, setting up, and running the controller loop.
Also add package documentation.
