Job rebuild icons should use POST instead of GET requests.

Job rebuild icons should use POST method instead of GET request after Jenkins version 1.502 (issue SECURITY-13).

Otherwise, it gives you the warning:
"You must use POST method to trigger builds. (From scripts you may instead pass a per-project authentication token, or authenticate with your API token.) If you see this page, it may be because a plugin offered a GET link; file a bug report for that plugin."