Sidebar Area Customization for overview pages

https://appirio-community.force.com/cmc/a4150000000EbHH

Deployment instructions: 
 - Activate Per Page Widgets plugin <== <!> Important
 - Change template of i.e. "Getting Started" Page to "Widgetized Overview Template"
 - In the page settings edit the Per Page Widget options
   - Set type to "Speciel"
   - Hide all SideBars except "Generic SideBar" which has to be set on "Special"
   - Edit Widgets
   - Add widgets to Generic SideBar: (Related_Content, Quote_Widget, Recent_challenges)

Summary:
 - Created new SideBar: "Generic SideBar"
 - Duplicated and modified "Overview Template" => "Widgetized Overview Template"
 - Added sidebar to the new template
 - Widgetized the 3 modules: Related_Content, Quote_Widget, Recent_challenges