-addattr
template: pers?clnt=<name|pass>&com=addattr&<attr_1>=<def_val_1>&<ftr_2>=...
          Order of query params is not important. Feature
          names must not end with '*' to be legal.
descript: inserts new (attribute, default value) pairs. Must
          be used while initializing the personalization service
          For attributes that are added at a later stage, the
          profile of all users is updated to include them as well.
          If one or more attribute names already exist in DB, or
          if one or more attribute names are not legal names,
          code 401 (request error) will be returned. If the
          error code 401 is returned then none of the feature
          pairs in the request has been inserted in the DB.
example : pers?clnt=name|pass&com=addattr&lang.en=0&lang.1=ENGLISH&lang.2=GREEK&gender=male
returns : 200 OK, 401 (fail, request error), 501 (fail, server error)
200 OK  : no response body exists.