code: function create(req, res, next) {
    var body = req.body
      , slug = string.slugify(body.title);
  
    db.tags.findBySlug(slug, function(err, tag) {
      if(err && err.statusCode != 404) { return next(err); }
  
      if(tag) {
        res.json(201, tag);
      } else {
        db.tags.create(req.body, function(err, tag) {
          if(err) {
            next(err);
          } else {
            res.json(201, tag);
            signals.emit('tag:create', tag);
          }
        });
      }
    });
  }
docs: URL: /tags/:tag
  
  Method: POST
  
  Events:
  
  * `tag:create` (tag)
  
  Status codes:
  
  * `201` if tag was created successfully
  * `409` if a tag with the same `slug` already exists