Upgrade Django to 1.5.4 to prevent DDoS by large password submission

The security issue fixed by the 1.5.4 release is detailed here:
https://www.djangoproject.com/weblog/2013/sep/15/security/
Signed-off-by: Balthazar Rouberol <brouberol@imap.cc>
Add ipdb to debug requirements

Signed-off-by: Balthazar Rouberol <brouberol@imap.cc>
Display the name of all the expense recipients in the list

Signed-off-by: Balthazar Rouberol <brouberol@imap.cc>