Improved /task/import endpoint
Status codes:
200 OKwhen no version was created;201 CREATEDand (absolute) uri of version in HTTPLocationheader when new version was created;
HTTP Link headers for Document, File, Version and Contents as well as json body in both 200 and 201 cases.
New query param asLatestVersion determines whether it is ok if the currently uploaded file already exists as any version or whether it has to be the latest version.
If any version is ok, no new version will be made if contents of current upload are already available as any version of this file.
if asLatestVersion is requested, new version will be made of this contents, unless these contents are already the current latest version.