golang format tools (#669)

Produced via:
  `gofmt -s -w $(find -path './vendor' -prune -o -type f -name '*.go' -print))`
  `goimports -w $(find -name '*.go' | grep -v vendor)`
/assign mattmoor

source/source_stats_reporter.go

@@ -18,9 +18,10 @@ package source
 
 import (
 	"context"
+	"strconv"
+
 	"go.opencensus.io/stats/view"
 	"knative.dev/pkg/metrics"
-	"strconv"
 
 	"go.opencensus.io/stats"
 	"go.opencensus.io/tag"

test/mako/alerter/slack/message_test.go

@@ -34,8 +34,8 @@ func TestMain(m *testing.M) {
 		config: repoConfig{
 			repo: "test_repo",
 			channels: []channel{
-				channel{name: "test_channel1", identity: "fsfdsf"},
-				channel{name: "test_channel2", identity: "fdsfhfdh"},
+				{name: "test_channel1", identity: "fsfdsf"},
+				{name: "test_channel2", identity: "fdsfhfdh"},
 			},
 		},
 		dryrun: false,

tracing/opencensus.go

@@ -9,7 +9,7 @@ import (
 
 	"contrib.go.opencensus.io/exporter/stackdriver"
 	oczipkin "contrib.go.opencensus.io/exporter/zipkin"
-	"github.com/openzipkin/zipkin-go"
+	zipkin "github.com/openzipkin/zipkin-go"
 	httpreporter "github.com/openzipkin/zipkin-go/reporter/http"
 	"go.opencensus.io/trace"
 	"go.uber.org/zap"