Admission control proposal

I am starting to look at how I can support some features that will require admission control, so wanted to get high-level agreement on the strategy so I can look to work on some of the more specific use cases we want to use admission control to achieve.

Feedback appreciated.
The major point is that all of these *could* be served by admission control plugin, and that there are a number of other potential use cases that were not enumerated here, so basic need for a flexible plug-point is all that I was advocating.

As for OpenShift, I plan to use admission control to satisfy 1 and 6 in the near term.  If we develop better alternatives for 3 and 5 - I think much of Volumes are still up in the air - then that is a-okay with me right now.