Fix bug 977391 - add GA tracking to contribute page
Bug 994831 - update history page

Replace previous history page with "15 facts" slideshow
Move previous history content to /history/details/
Merge pull request #1981 from mozilla/bug-994831-history-slideshow

Bug 994831 - update history page
Merge pull request #1985 from craigcook/bug-977391-add-tracking-to-contribute

Fix bug 977391 - add GA tracking to contribute page