G cloud bug fixes

Some bug fixes for G-Cloud. 

* Wording changes following discussion with Phil
* Add missing stub option to match main dashboard
* Related links should use relative paths and not open in new tab
* Fix hover and date display bugs on completion_rate graphs by simply removing null data from the series. 

Pull requests for last point: 
https://www.pivotaltracker.com/s/projects/911874/stories/64157358
and hopefully will fix: 
https://www.pivotaltracker.com/s/projects/911874/stories/64158244