rename "Open Badge(s) Backpack" -> "Mozilla Backpack"

 * fixes issue #790
Merge branch 'development' of git://github.com/mozilla/openbadges into development
set login page title back to "Welcome to your Backpack"

 * modifying pull request #827 which is for issue #790
Merge pull request #827 from arasbm/development

rename "Open Badge(s) Backpack" -> "Mozilla Backpack"