Google Code-in

In this task related to django-x509, one of the OpenWISP 2 base modules, there's some quality assurance but also some coding involved.

Find why the build for pull request #17 is failing and propose a fix. This means cloning the branch from which the pull request is made (issues/14), replicate the bug locally in your development environment, adding the commit that solves it and then sending a pull request to the same branch (issues/14).

Ensure to write a brief explaination of what was wrong in the commit message long description (not the first line). Ensure the commit message is also copied in the pull request.