some dpl-docs fixes (building docs 2.066.1)

- fixate dub.selections.json to a compilable vibe-d+dependencies combination

- fix disqus plugin for HTTPS

- remove google add footer
I think that this "powered by Disqus" text can be removed, as the Disqus system puts a similar text anyway.
![untitled](https://cloud.githubusercontent.com/assets/5781692/4658429/5e3465a6-54fe-11e4-97de-d573b6d7c564.png)