Endpoints: * List All Tags [GET] * Get a tag [GET] * Update a tag [PUT] * Delete a tag [DELETE] Fixes #904 References shaarli/api-documentation#34
See http://shaarli.github.io/api-documentation/#links-link-get
* REST API routes are handle by Slim. * Every API controller go through ApiMiddleware which handles security. * First service implemented `/info`, for tests purpose.