removed zones.c from repo, xfr-handler.c from build

Knot.files

src/Makefile.am

src/knot/nameserver/axfr.c

src/knot/nameserver/axfr.h

src/knot/nameserver/ixfr.c

src/knot/nameserver/ixfr.h

src/knot/nameserver/update.c

src/knot/server/tcp-handler.c

src/knot/server/tcp-handler.h

src/knot/server/xfr-handler.c

src/knot/server/zone-load.c

src/knot/server/zones.c