Allow new draft to be created after content has been published

When posting to /users/contents with an "id", authoring will first look
for a draft in authoring, if the draft is not "Done/Success", authoring
will return that, otherwise authoring will first remove the published
draft and create a new one.
Merge pull request #113 from Connexions/edit-after-publish2

Allow new draft to be created after content has been published