anchor.diff:  --
   User Authentication Status API
   
  -When Searchisko is configured to work with authentication server (like SSO) then the following endpoint can be used to
  -learn if user has been successfully authenticated.
  ---
  -
  -Learn if user has been authenticated.
  +When Searchisko REST API is called directly from Web browser, and Searchisko is configured to cooperate with web SSO authentication server, 
  +then this endpoint can be used from JavaScript to check if user is authenticated. 
  +This information can be used then to show user necessary controls and/or to perform call to other Searchisko APIs used to obtain personalized 
  +data (like 'content rating' endpoint).  
  +--
  +
  +Check if user is authenticated.
  +
  +##### Response content
  +The response contains a JSON object with `authenticated` field. Value `true` means user is authenticated:
  +
  +```
  +{
  +  "authenticated":true
  +}
  +```
   
   GET /rest/auth/status
   < 200
  
positive.code: {
    "authenticated":true
  }
  
  
  --
  
negative.code: * `search_result_uuid` - value of `uuid` field from search response this statistics record is for 
  * `hit_id` - unique identifier of search hit document (`hits/hits[]/_id` field 
  in response) from given search response which was "useful" for user (eg. he clicked it 
  or viewed detail). Validation is performed during server side record write to ensure this 
  identifier has been part of given search response. 
  * `session_id` - optional, identifier of user's frontend session to allow more precise user behavior analyze
  
  PUT /rest/search/{search_result_uuid}/{hit_id}?{session_id}
  