Adding all_extensions method to Language

lib/linguist/language.rb

@@ -426,6 +426,11 @@ module Linguist
     #
     # Returns the extensions Array
     attr_reader :filenames
+    
+    # Public: Return all possible extensions for language
+    def all_extensions
+      (extensions + [primary_extension]).uniq
+    end
 
     # Public: Get URL escaped name.
     #