Tackling GTM promote/reconnect

Okay, now GTM/Proxy works with configuration file under NODE_NAME extension.

Now, promote/reconnect.   Promote looked to work but in reality, it didn't.   Somehow, promoted standby tries to register itself to itself and this doesn't work obviously.   I need to find how this happens, because it worked fine before NODE_NAME work (node id, instead).

One idea: Should we change the way of "register" to connection negotiation to tell GTM who I am, coordinator/datanode/gtm_proxy/gtm_standby.   Although this has very little to do with registering self....

Another thing about current GTM protocol is that strings are not NULL-Terminated.   Strings has a prefix to indicate the length of the string.    That's find.   However, the following string is not null-terminated and the recipient has to reconstruct these strings to null-terminated strings, which increase number of lines of code and could be very good cause of failure.