Remove dead code

(found by looking for https://www.djangoproject.com/weblog/2014/mar/22/strip-tags-advisory/)
Fix #102 - Show canceled purchases in profile area

Canceled purchases are now shown in the profile area, with a warning and
without the button to resend invoices.
Add translation for canceled purchase message
Merge pull request #107 from DasIch/show-canceled

Fix #102 - Show canceled purchases in profile area