For #194, convert the POTD management command to a celery task. Refactored to put the logic for the command into a function, and the command simply calls this function. The task can also just call this function. Added some basic tests for the new function.

{% extends 'base.html' %}
{% block custom_css %}
<link rel="stylesheet" type="text/css" href="{{ STATIC_URL }}css/bio.css" />
{% block bio_css %}{% endblock %}
{% endblock %}
{% block content %}
{% endblock %}