add browser detection

app/assets/javascripts/browser_detection.js

+jQuery.browser = {};
+jQuery.browser.mozilla = /mozilla/.test(navigator.userAgent.toLowerCase()) && !/webkit/.test(navigator.userAgent.toLowerCase());
+jQuery.browser.webkit = /webkit/.test(navigator.userAgent.toLowerCase());
+jQuery.browser.opera = /opera/.test(navigator.userAgent.toLowerCase());
+jQuery.browser.msie = /msie/.test(navigator.userAgent.toLowerCase());

app/assets/javascripts/main.js

@@ -11,6 +11,7 @@
 //= require jquery.placeholder
 //= require rails-timeago
 //= require facebox
+//= require browser_detection
 //= require jquery.events.input
 //= require jquery.elastic
 //= require jquery.mentionsInput