Promote other browsers than Firefox

Issue Summary

IE Destroyer now allows you to choose whether you want to promote Firefox, Opera or Safari. Messages can now contain wild cards that will be replaced by the name and download link of the browser than you want to promote. It is therefore extremely to instantly promote another browser: you don't have to change you messages, just select the new browser and hit 'enter'.

Added and committed to 5.x-1.x-dev.