Add addressed field in question.
Add ribbon for answered questions.
Merge pull request #83 from akatsoulas/address-question

Add ribbon for answered questions.
Add reveal.js lib.
Admin replies to questions functionality.

* Add reply form only for admins.
* Show replies in replied questions.
* Add datamigration for "Admin" group.
* Add reply field in questions.
Do not use underscore in classes.
Show only archived events in archive.