Alias macron package in app_routes.go

...to make this file compatible with goimports:
https://godoc.org/golang.org/x/tools/cmd/goimports

pkg/api/app_routes.go

@@ -6,14 +6,13 @@ import (
 	"net/http"
 	"time"
 
-	"gopkg.in/macaron.v1"
-
 	"github.com/grafana/grafana/pkg/api/pluginproxy"
 	"github.com/grafana/grafana/pkg/log"
 	"github.com/grafana/grafana/pkg/middleware"
 	m "github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/plugins"
 	"github.com/grafana/grafana/pkg/util"
+	macaron "gopkg.in/macaron.v1"
 )
 
 var pluginProxyTransport = &http.Transport{