Deprecation of obsolescent decorators

[BurtHarris]

Would you be open to a PR including completing the deprecation of those decorators marked obsolescent?

This, obviously, would be a breaking change. Perhaps a good time to bump the major version number up to 1, which (IMHO) would make the package more attractive.

[jayphelps]

@BurtHarris I'd be down with a PR to remove those decorators. I don't want to go 1.0, however. I intentionally don't want to make core-decorators appear more attractive or more stable than it really is--the decorators spec is too unstable and since this is a stage-0 version I actually would prefer no new people use it. They're just setting themselves up for future pain.

This library was made to flex the spec and find issues with it, which worked really well, but I (and others) have learned people adopt stage-0 and stage-1 things without understanding the repercussions and they complain about the growing pains and instability they should have expected.