Update knowledgebase_helper.rb

Line 20: the date (24 Feb 2014)  is more concise than the complete TimeStamp (Mon, 24 Feb 2014 23:21:17 +0000) for this section. This is a personal suggestion. 

Line 106: Redmine 2.1.1 moved to Rails 3, so there is no link_to_remote We must test for the 3rd digit not only 2.1