Bug 1289830 - Block ActiveData's user agent due to excessive requests

ActiveData's scraping of Treeherder's API has caused responsiveness and
performance issues for other users of Treeherder on several occasions,
so is being blocked until we can decide upon a less detrimental way for
ActiveData to obtain this data.

treeherder/config/settings.py

@@ -338,6 +338,8 @@ DISALLOWED_USER_AGENTS = (
     re.compile(r'^libcurl/'),
     re.compile(r'^Python-urllib/'),
     re.compile(r'^python-requests/'),
+    # ActiveData blocked for excessive API requests (bug 1289830)
+    re.compile(r'^ActiveData-ETL'),
 )
 
 SITE_URL = env("SITE_URL", default="http://local.treeherder.mozilla.org")