new ADCs to replace internal setdesc and getdesc

[Sitaram Chamarty]

[Hi list: John wanted to allow anyone with RW+ permissions to
"setdesc" a non-wild repo. In case there are others who need
this, I'm copying this to the list.]

Hi John,

These ADCs override the internal setdesc/getdesc commands. (An
ADC can override any internal command; this is by design. You
can name them differently if you don't want to override the
internal ones).

I did some testing and they seemed to work OK. They will be
shipping with the next push, whenever that is, but will be
shipped 'chmod -x' so that the gitolite admin has to explicitly
'chmod +x' them for it to happen.

(This extra protection is because these ADCs are looser in their
definition of who may set description -- only RW+ on master
branch required, versus actually being the "owner").

regards

sitaram