+ iAppendInFile: append sth to the attribute's value.
* iKeyAlias: create a key alias and add the alias to the alias attribute.
  + append the alias to the ".alias" attribute after creating key alias successful
  * the aliases seperate from "\n".
* !iDeleteKey:
  + check the delete key whether is a key alias
  + delete all aliases from ".alias" attribute if not an alias
  * remove all aliases first if the key is not a alias.
+ AppendInFileSync/Async functions and test