Bump version to 0.16rc3
dnshook: Fix broken function invocation

Commit 84a92e7b5 introduced a bug wrt function calling.
Fix this by renaming update_all() to update_dns().

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
dnshook: Report if nsupdate succeeded or not

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>