Move find article logic to a struts action

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.0.5 GA
• Fix Version/s: --Sprint - SP, 6.1.0 CE RC1
• Component/s: Knowledge Base widget
• Labels: None
• Branch Version/s:
  6.0.x
• Backported to Branch:
  Committed

This follows the pattern in core for dynamically finding assets.

Blogs -> FindEntryAction.java -> /blogs/find_entry?entryId=x
MB -> FindMessageAction.java -> /message_boards/find_message?messageId=x
KB -> FindArticleAction.java -> /portal/knowledge_base/find_article?=resourcePrimKey=x

Use KnowledgeBaseUtil.getArticleURL(...) to create the link.