Bump plugin version to 5.0.0

Author: alexbevi

init.rb

@@ -20,7 +20,7 @@
   author_url  "http://www.alexbevi.com"
   description 'A plugin for Redmine that adds knowledgebase functionality'
   url         'https://github.com/alexbevi/redmine_knowledgebase'
-  version     '4.1.1'
+  version     '5.0.0'
 
   requires_redmine :version_or_higher => '4.0.0'