Use channel in messaging between goroutine instead of zmq.REQ

This will resolve socket exhaust problem on high concurrency.

refs #160

.gogocyclo

@@ -4,3 +4,4 @@ ignores = `pq`.(*recordScanner).Scan
 ignores = `pq`.(*database).remoteColumnTypes
 ignores = `skydb`.(Predicate).Validate
 ignores = `skyconv`.ParseLiteral
+ignores = `zmq`.(*Broker).Run

.travis.yml

@@ -1,6 +1,6 @@
 language: go
 
-go: 1.6
+go: 1.6.3
 
 addons:
   postgresql: "9.5"
@@ -49,7 +49,7 @@ script:
   - go generate ./pkg/...
   - git status | grep "_string.go$"; test $? -eq 1
   - gocyclo -over 15 pkg | gogocyclo
-  - go test --tags zmq -cover -timeout 1m ./pkg/...
+  - WITH_ZMQ=1 make test
 
 before_deploy:
   - if [[ -z "$TRAVIS_TAG" ]]; then make all; fi

Makefile

@@ -48,7 +48,7 @@ before-test:
 test:
 	# Run `go install` to compile packages to speed up test process
 	$(DOCKER_COMPOSE_RUN) go install $(GO_BUILD_ARGS)
-	$(DOCKER_COMPOSE_RUN) go test $(GO_BUILD_ARGS) -cover -timeout $(GO_TEST_TIMEOUT) ./pkg/...
+	$(DOCKER_COMPOSE_RUN) go test $(GO_BUILD_ARGS) -cover -timeout $(GO_TEST_TIMEOUT) -cpu 1,4 ./pkg/...
 
 .PHONY: after-docker-test
 after-docker-test: