Convert installation to Bootstrap design, refactor client-side validation to be Bootstrap/HTML5 compatible, update style of backup/export pages

* Upgraded detect_timezone.js to jstz-1.0.4.min.js, to bring in 3 years' worth of updates
* Replace older jquery.validate.js in installation with jqBootstrapValidation.js (older validate still used in registration flow)
* Update necessary tests for copy changes in installation screens