contrib: remove ciabot

Almost a year ago the CIA service irrevocably crashed.  The CIA author
had plans to revive the service, but the effort has since sunk without
trace.

Projects tend to use "irker" instead these days.  Repository hook
scripts for irker ship with the irker distribution.

Signed-off-by: Stefan Beller <[email protected]>
Acked-by: Eric S. Raymond <[email protected]>
Signed-off-by: Jonathan Nieder <[email protected]>

Author: stefanbeller