add: ussd and cache syncer tasks

- no repeat on failure, picked up on next schedule
- enforce uniq on users and tx table to prevent duplicates

Makefile

@@ -0,0 +1,5 @@
+BIN := cic-dw
+
+.PHONY: build
+build:
+	CGO_ENABLED=1 GOOS=linux go build -o ${BIN} -ldflags="-s -w" cmd/*.go