Is there any workaround to install iOS 7 after Apple are longer signing it?
There is a jailbreak available for iOS 8.1 now!  PanGu will jailbreak the iPhone 5, but you have to manually install Cydia.  Either using WinSCP for Windows or Cyberduck for Mac in conjunction with a command line and SSH into the iPhone 5.  One more thing, there is almost nothing available for the iPhone as the jailbreak just came out and everyone is scrambling to update tweaks to run on iOS 8.1.  But you can have at, "Hey Siri" all you want while taking phone calls on your iPad and sending texts from your Mac!

Oh, and I know you posted this a month ago, but figured this MAY help!