[#956] Mention that Emacs 24.4 is required

Some packages are now depending on Emacs 24.4 (e.g. magit).

README.md

@@ -13,7 +13,7 @@ library to the mix. The final product offers an easy to use Emacs
 configuration for Emacs newcomers and lots of additional power for
 Emacs power users.
 
-Prelude is compatible **ONLY with GNU Emacs 24.x**. In general you're
+Prelude is compatible **ONLY with GNU Emacs 24.4+**. In general you're
 advised to always run Prelude with the latest Emacs - currently
 **24.5**.
 

init.el

@@ -38,8 +38,8 @@
 
 (message "Prelude is powering up... Be patient, Master %s!" current-user)
 
-(when (version< emacs-version "24.1")
-  (error "Prelude requires at least GNU Emacs 24.1, but you're running %s" emacs-version))
+(when (version< emacs-version "24.4")
+  (error "Prelude requires at least GNU Emacs 24.4, but you're running %s" emacs-version))
 
 ;; Always load newest byte code
 (setq load-prefer-newer t)