state/apiserver: move api/params to apiserver/params

This PR moves api/params to apiserver/params. The justification is the params package defines the form of the api messages that the server will accept, not the form that the client will provide.

This move makes it clear that the parameters belong to the apiserver, not a Go implementation of the api client.
Merge branch 'master' of https://github.com/juju/juju into 190-move-state-api-params-to-state-apiserver-params
gofmt
Merge pull request #653 from davecheney/190-move-state-api-params-to-state-apiserver-params

state/apiserver: move api/params to apiserver/params

This PR moves `api/params` to `apiserver/params`. The justification is the `params` package defines the form of the api messages that the server will accept, not the form that the client will provide.

This move makes it clear that the parameters belong to the `apiserver`, not a Go implementation of the api client.