code: function _lookupKeyInPair(pair) {
    var key = pair[0];
    var value = pair[1];
    return Bluebird.all([
      this.lookupCriteriaKey(key),
      value
    ]);
  }
docs: Query DFP for the key id of a key value pair.
  
  @param  {Array} pair [0] The name of a key.
  [1] The name of a value.
  @return {Promise}    Resolves with an Array
  [0] The dfp id of the key passed in.
  [1] The name of value passed in (unchanged).