Implement export and compression of files for webonary upload

* Introduce publish to webonary controller and tests
* Add code to controller to export xhtml and css
* Add code to controller to compress exported files

Change-Id: I01d08919add74c5935e2f66459b7d6ce39029974
Fix a crash trying to reset settings if there are no settings

Change-Id: I99a6fa214e95d4b2a94b03be727821a5592db070