anchor.diff:  
   + Response 400 (application/json)
   
  +    When attempting to temperature data for date **already in the database**
  +    with a POST request, you get an error in the JSON response.
  +
       + Body
   
               {
                   "message": "Data for 20170215 already exists"
               }
               
  +
  +## Temperature Data - Add/Retrieve a Single Day [/historical/{date}]
  +
  +The temperature data for a single date in the past is retrieved by adding `{date}` in
  +ISO8601 format (`YYYYMMDD`) to the end of the `/historical/` resource.
  +
  +Attempting to retrieve dates which don't exist in the datbase will yield a
  +`Data for <date> already exists` message in the JSON response.
  +
  ++ Parameters
  +
  +    + date (string) - date for which to fetch data (`YYYYMMDD` format)
  +
  +### Get temperatures for a single day in the past [GET]
  +
  ++ Response 200 (application/json)
  +
  +    + Body
  +
  +            {
  +                "DATE": "20170215",
  +                "TMAX": 62.0,
  +                "TMIN": 45.0
  +            }
  +            
  ++ Response 404 (application/json)
  +
  +    When attempting to get temperatures for a day **not in the database**,
  +    you get an error message in the JSON response.
  +    
  +    + Body 
  +
  +            {
  +                "message": "No data found for 99990101"
  +            }
  +            
  +### Delete temperature for a single day [DELETE]
  +
  ++ Response 204
  +
  ++ Response 404 (application/json)
  +
  +    When attempting to delete the record for a day **not in the database**, you
  +    get an error message in the JSON response.
  +    
  +    + Body
  +
  +            {
  +                "message": "No data found for 99990101"
  +            }
  +
  +
   ## Add New Data with GET Request [/historical/{?DATE,TMAX,TMIN}]
   
   For adding new data to the database, the POST method probably makes more sense
  
positive.code:                 "DATE": "20170215"
              }
  
  ### Add temperature data for date already in the database - GET [POST]
  
  + Response 400 (application/json)
  
      + Body
  
              {
                  "message": "Data for 20170215 already exists"
              }
  
  
  ## Temperature Data - Single Day [/historical/{date}]
  
  The temperature data for a single date in the past is retrieved by adding `{date}` in
  ISO8601 format (`YYYYMMDD`) to the end of the `/historical/` resource.
  
  Attempting to retrieve dates which don't exist in the datbase will yield a
  `Data for <date> already exists` message in the JSON response.
  
  + Parameters
  
      + date (string) - date for which to fetch data (`YYYYMMDD` format)
  
  ### Get temperatures for a single day in the past [GET]
  
  
  + Response 200 (application/json)
  
      + Body
  
              {
                  "DATE": "20170215",
                  "TMAX": 62.0,
                  "TMIN": 45.0
              }
              
  ### Get temperatures for a single day not in the database [GET]
  
  + Response 404 (application/json)
  
          {
              "message": "No data found for 99990101"
          }
              
  ### Delete temperature for a single day [DELETE]
  
  + Response 204
  
  ### Delete temperature for a day not in the database [DELETE]
  
  + Response 404 (application/json)
  
          {
              "message": "No data found for 99990101"
          }
negative.code:             {
                  "DATE": "20170215"
              }
  
  + Request (application/json)
  
  