enable cache for build, closes #8 (#12)

* enable cache for build, closes #8
* goimports
* lint fixes

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

selector/roundrobin/roundrobin_test.go

@@ -3,8 +3,8 @@ package roundrobin
 import (
 	"testing"
 
-	"github.com/unistack-org/micro/v3/selector"
 	"github.com/stretchr/testify/assert"
+	"github.com/unistack-org/micro/v3/selector"
 )
 
 func TestRoundRobin(t *testing.T) {