Added translation methods to JS and Python

Modified "Create"-form

templates/categories.html

@@ -0,0 +1,9 @@
+<!--
+vim: ts=2 noexpandtab
+-->
+{% extends "index.html" %}
+{% block title %}{{ super() }} - Categories{% endblock%}
+{% set active_page = "categories" %}
+{% block content %}
+<p>CATEGORIES</p>
+{% endblock content%}