Document upload

* adds document upload form
* refactors modal form templates into form classes
* adds document upload route to intervention routes of urls.py

templates/table/generic_table_form.html

@@ -14,7 +14,7 @@
         {{ form.form_caption }}
     </small>
     {% endif %}
-    <form method="post" action="{{ form.action_url }}">
+    <form method="post" action="{{ form.action_url }}" {% for attr_key, attr_val in form.form_attrs.items %} {{attr_key}}="{{attr_val}}"{% endfor %}>
         {% csrf_token %}
         {% include 'table/generic_table_form_body.html' %}
         <div class="row">