code: function isUnique(str, options){
          var deferred = q.defer(),
              qry = [ { key: options.property, cmp: '=', value: str } ];
  
          db.content.query([], options.contentTypes, qry, {} ).then(
              function(payload) {
                  if(payload.total === 0){
                      deferred.resolve(true);
                  }
                  else {
                      deferred.reject(false);
                  }
              }
          );
  
          return deferred.promise;
      }
docs: Function that will check to see if a passed in property exists in the system. By default it will check all
  content types. If you pass one/many content types along in the options then it will narrow it's search
  to the desired content types.
  
  @param str Value to be tested for uniqueness
  @param options { property: 'fields.property', contentTypes: [ 'contentTypeID' ] }
  @returns {*}