contint: prevent SISTRIX Crawler from browsing Jenkins

Change-Id: Ie8685da13c6f9340d81fcfbe385a4ca338fa46d7
User-agent: SISTRIX Crawler; http://crawler.sistrix.net/
contint: deny access to RSS feeds on main Jenkins page

Some more URL that are killing Jenkins, attempting to LazyLoad all
builds:

 /ci/rssAll
 /ci/rssFailed
 /ci/rssLatest

Change-Id: Ic02f58c38909cd711db6153c5065f8469b2c17f2
Merge changes Ic02f58c3,Ie8685da1 into production

* changes:
  contint: deny access to RSS feeds on main Jenkins page
  contint: prevent SISTRIX Crawler from browsing Jenkins