Add linum-relative module

It doesn't activate by default, but it's available for when I want it.

modules/siren-linum-relative.el

@@ -0,0 +1,9 @@
+;;
+;; linum-relative
+;;
+
+(siren-require-packages '(linum-relative))
+(require 'linum-relative)
+
+
+(provide 'siren-linum-relative)

siren-modules.el

@@ -18,6 +18,7 @@
 (require 'siren-helm)
 (require 'siren-ido)
 (require 'siren-linum)
+(require 'siren-linum-relative)
 (require 'siren-magit)
 (require 'siren-move-beginning-of-line)
 (require 'siren-multiple-cursors)