state/multiwatcher: move remaining mutliwatcher related types
tests pass
remove unused types
remove vestigial type decl
Merge branch 'master' of https://github.com/juju/juju into 212-state-multiwatcher-info-types
responding to review feedback
Merge branch 'master' of https://github.com/juju/juju into 212-state-multiwatcher-info-types

Conflicts:
	apiserver/params/internal.go
gofmt
Merge pull request #1116 from davecheney/212-state-multiwatcher-info-types

state/multiwatcher: move remaining mutliwatcher related types

Followup to #1108 

It's pretty clear that these other types belong to the multiwatcher.