Added archive view, label editing

Archives can now be viewed, a cover can optionally be inserted into the covers directory.
Labels can now be edited.

flask/templates/labels.html

@@ -0,0 +1,21 @@
+{% extends "base.html" %}
+
+{% block meta %}
+<link rel="stylesheet" href="/static/view.css" />
+{% endblock %}
+
+{% block content %}
+<h2>{{archive[1]}}</h2>
+<form action="/labels/{{archive[0]}}" method="post">
+    <div class="flex-container">
+        {% for ltype in res_labels %}
+        <div class="flex-item"><b>{{ltype}}</b>
+            {% for for_temp in res_labels[ltype] %}
+            <input type="checkbox" id="{{for_temp[0]}}" name="{{for_temp[0]}}" {% if for_temp[1] in labels_names %}checked{% endif %}><label for="{{for_temp[0]}}">{{for_temp[1]}}</label>
+            {% endfor %}
+        </div>
+        {% endfor %}
+    </div>
+    <input type="submit" value="Submit">
+</form>
+{% endblock %}