Milo buildbot builder page: Add pagnation with cursors.

milo/appengine/frontend/templates/pages/builder.html

 {{define "title"}}Builder {{ .Builder.Name }}{{end}}
 
 {{define "head"}}
 <link id="favicon" rel="shortcut icon"
       type="image/png" href="/static/common/favicon/milo-32.png">
 {{end}}
 
 {{define "body"}}
-<h1>Builder {{.Builder.Name}}</h1>
+<h1>Builder <a href="{{ pagedURL .Request -1 "EMPTY" }}">{{.Builder.Name}}</a></h1>
 
 {{ if .Builder.CurrentBuilds }}
   <h2>Current Builds ({{len .Builder.CurrentBuilds}}):</h2>
   <ul>
   {{ range .Builder.CurrentBuilds }}
     <li>{{ .Link | linkify }}
       {{ $nb := len .Blame }}
       {{ if lt $nb 4 }}
         {{ range $i, $c := .Blame }}
           {{ if gt $i 0 }},{{ end }}
@@ skipping 92 matching lines @@
             {{ . }}
           {{ end }}
         </td>
       </tr>
     {{ end }}
   </table>
 {{ else }}
   <h2>No Recent Builds</h2>
 {{ end }}
 
+{{ if .Builder.PrevCursor }}<a href="{{ pagedURL .Request 0 .Builder.PrevCursor }}">Prev</a>{{ end }}
 (Show:
-<a href=".">default</a>
-<a href="?limit=25">25</a>
-<a href="?limit=50">50</a>
-<a href="?limit=100">100</a>
-<a href="?limit=200">200</a>
+<a href="{{ pagedURL .Request -1 "" }}">default</a>
+<a href="{{ pagedURL .Request 25 "" }}">25</a>
+<a href="{{ pagedURL .Request 50 "" }}">50</a>
+<a href="{{ pagedURL .Request 100 "" }}">100</a>
+<a href="{{ pagedURL .Request 200 "" }}">200</a>
 )
+{{ if .Builder.NextCursor }}<a href="{{ pagedURL .Request 0 .Builder.NextCursor}}">Next</a>{{ end }}
 
 {{end}}