Cleanup deprecated api
Merge pull request #98 from ctomc/managmenet

Cleanup deprecated api
Hide internal implementation classes in ExtensionRegistry
Don't use deprecated ExtensionRegistry constructor
Remove deprecated getExtensionContext variant
ExtensionRegistry should not cache any ManagementResourceRegistration so it won't use the wrong one if it's cloned
[WFCORE-21] Revert ExtensionRegistry changes if the operation that made them rolls back
Introduce an encapsulation of the various elements of the management model
Use it support the copy-on-write/publish-on-commit semantic for ops that make management model changes
cap-req WIP