scheduler: rename JobID to JobName to avoid overloading JobID meaning.

scheduler/appengine/frontend/templates/pages/invocation.html

-{{define "title"}}LUCI Scheduler :: {{.Job.ProjectID}} :: {{.Job.JobID}} :: {{.Inv.InvID}}{{end}}
+{{define "title"}}LUCI Scheduler :: {{.Job.ProjectID}} :: {{.Job.JobName}} :: {{.Inv.InvID}}{{end}}
 
 {{define "head"}}
 <style type="text/css">
 .underline {
   text-decoration: underline !important;
 }
 </style>
 {{template "invocation-action-scripts" .}}
 {{end}}
 
 {{define "content"}}
 
 <ol class="breadcrumb">
   <li><a href="/">All projects</a></li>
   <li><a href="/jobs/{{.Job.ProjectID}}">{{.Job.ProjectID}}</a></li>
   <li>{{template "job-id-ref" .Job}}</li>
-  <li class="active"><a href="/jobs/{{.Job.ProjectID}}/{{.Job.JobID}}/{{.Inv.InvID}}">{{.Inv.InvID}}</a></li>
+  <li class="active"><a href="/jobs/{{.Job.ProjectID}}/{{.Job.JobName}}/{{.Inv.InvID}}">{{.Inv.InvID}}</a></li>
 </ol>
 
 <div class="container">
   <div class="row">
     <div class="col-sm-3"><b>Status:</b>
       {{if .Inv.ViewURL}}
         <a href="{{.Inv.ViewURL}}" target="_blank" class="underline label {{.Inv.LabelClass}}">{{.Inv.Status}}</a>
       {{else}}
         <span class="label {{.Inv.LabelClass}}">{{.Inv.Status}}</span>
       {{end}}
@@ skipping 25 matching lines @@
   <h4>Debug log (UTC)</h4>
   <div class="row">
     <div class="col-sm-12">
       <pre>{{.Inv.DebugLog}}</pre>
     </div>
   </div>
 
 </div>
 
 {{end}}