This moves the common Condition stuff to apis, and creates a v1beta1 form of Status that uses the Condition it defines (changing this in v1alpha1 is too breaking).
There aren't really any meaningful changes in this PR, mostly reorganization. Enumerating what I did:
1. Copied `condition_set*.go` to `apis/`,
1. Copied the `Condition` portions of `conditions_types.go` to `apis/`,
1. Copied the balance of `conditions_types.go` to `apis/duck/v1beta1/status_types.go`,
1. Changed the parts of the above to reference things in the appropriate new places,
1. Removed the reflection-based `ConditionsAccessor` stuff, implementing it instead on `duckv1beta1.Status`.
1. Incorporate: https://github.com/knative/pkg/pull/358
Matt Moore