Add danger alert to application pages for not supporting IE8
Move IE8 alert into partial and include in application and devise layouts instead
Update to <=IE8, remove inline styles, move alert to top of body
Add link in alert to updateyourbrowser.net
Update alert to jumbotron with alert styles
Remove text-align since it does not correctly center the text on IE8
Remove unused class from stylesheet, remove extra period in warning message
Merge branch 'detect_ie8'; fixes #253