Bug 1023292 - split up browser_popupNotification.js r=adw,MattN

--HG--
rename : browser/base/content/test/general/browser_popupNotification.js => browser/base/content/test/popupNotifications/browser_popupNotification.js
rename : browser/base/content/test/general/browser_popupNotification.js => browser/base/content/test/popupNotifications/browser_popupNotification_2.js
rename : browser/base/content/test/general/browser_popupNotification.js => browser/base/content/test/popupNotifications/browser_popupNotification_3.js
rename : browser/base/content/test/general/browser_popupNotification.js => browser/base/content/test/popupNotifications/browser_popupNotification_4.js
rename : browser/base/content/test/general/head.js => browser/base/content/test/popupNotifications/head.js