anchor.diff:  POST /lps/{lpID}/mv-md
   > Authorization: MAC id="...", ts="...", nonce="...", mac="..."
   {
  -    "identifyingFields": 
  +    "identifying_factors": 
       [
           {
               "fieldKey": "member_first_name",
  
positive.code: mvType field refers to the type of MV requested, which will set the expiry on the MV
  </br>If invalid fields are passed, return a 400 (Bad Request)
  </br>If LP Service is unavailable for any reason, return a 503 (Service Unavailable)
  POST /lps/{lpID}/mv
  > Content-Type: application/json;charset=utf-8
  > Authorization: MAC id="...", ts="...", nonce="...", mac="..."
  {
      "memberFields": {
  
negative.code: }
  < 201
  {
      "identifying_factors": 
      [
          {
              "fieldKey": "member_first_name",
  