[extensions-web] add missing sorl-thumbnail from requirements.txt

[Frederic Peters <fpeters src gnome org>]

commit b5184da589dd9aae5be851cd3fdb0b27bcb91d73
Author: Frédéric Péters <fpeters 0d be>
Date:   Mon Apr 6 10:10:52 2015 +0200

    add missing sorl-thumbnail from requirements.txt

 requirements.txt |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/requirements.txt b/requirements.txt
index 79a8771..75c778a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,3 +4,4 @@ django-autoslug==1.4.1
 django-registration==0.7
 wsgiref==0.1.2
 South==0.7.3
+sorl-thumbnail