Turn chasquid-userdb into chasquid-util

This patch removes chasquid-userdb and adds a more generic and extensive
chasquid-util, that supports various operations on user databases as well as
aliases lookups.

The code is not very pretty but for now I took a more practical approach, the
tool is ancillary and can be tidied up later.

test/util/lib.sh

@@ -35,10 +35,8 @@ function chasquid() {
 }
 
 function add_user() {
-	go run ${TBASE}/../../cmd/chasquid-userdb/chasquid-userdb.go \
-		--database "config/domains/${1}/users" \
-		--add_user "${2}" \
-		--password "${3}" \
+	go run ${TBASE}/../../cmd/chasquid-util/chasquid-util.go \
+		adduser "config/domains/${1}/users" "${2}" --password "${3}" \
 		>> .add_user_logs
 }