[regrep] Error Handling in RS 2.0

[Chaemee Kim <cmkim@ktnet.com>]

Dear members,

I'd like to suggest "Error Code" in Error Handling for each registry service.
In RS 1.0, we don;t have error list guideline, so KTNET made our own error list to notify it to registry client program.
In RS 2.0 draft, I'm so happy that we add error handling.
However, there is not error code. 

I think some error code system is very useful to detect error and take some action in registry client program.

Business Rule + Applies To + Error/Warning + Code(Number)

Happy New Year & Good Luck!