remove unnecessary scrollbar in badge accept modals

 * this fixes #775
fixing scrollbar conflict with bootstrap fluid grid

* add to pull request #829
* should fix bug #775
Merge branch 'development' of git://github.com/mozilla/openbadges into development
Merge branch 'development' of git://github.com/mozilla/openbadges into development
Merge pull request #829 from arasbm/development

remove unnecessary scrollbar in badge accept modals