Browser: Add a very basic content filter list

Let's start out with something small, just to make sure the feature
gets tested.

Base/home/anon/.config/BrowserContentFilters.txt

@@ -0,0 +1,24 @@
+207.net
+247realmedia.com
+2o7.net
+adbrite.com
+admob.com
+adthis.com
+advertising.com
+aquantive.com
+atwola.com
+channelintelligence.com
+doubleclick.com
+doubleclick.net
+esomniture.com
+google-analytics.com
+googleadservices.com
+googlesyndication.com
+gravity.com
+hitbox.com
+intellitxt.com
+nielsen-online.com
+omniture.com
+quantcast.com
+quantserve.com
+scorecardresearch.com