[milo] {buildbucket,buildbot,swarming,logdog} -> backends/*.

milo/appengine/job_source/buildbot/html.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package buildbot
 
 import (
         "fmt"
         "net/http"
         "strconv"
@@ skipping 80 matching lines @@
                 })
         case err == errNotAuth:
                 common.ErrorPage(c, http.StatusUnauthorized, err.Error())
         case notFound:
                 common.ErrorPage(c, http.StatusNotFound, err.Error())
         default: // err != nil
                 common.ErrorPage(c, http.StatusInternalServerError, err.Error())
         }
         return
 }