Nicer display of roster filter and add labels to chatrooms form

src/templates/room_panel.html

 <form class="add-chatroom" action="" method="post">
+    <label>{{label_room_name}}</label>
     <input type="text" name="chatroom" class="new-chatroom-name"
         placeholder="{{label_room_name}}"/>
+    <label>{{label_nickname}}</label>
     <input type="text" name="nick" class="new-chatroom-nick"
         placeholder="{{label_nickname}}"/>
+    <label>{{label_server}}</label>
     <input type="{{server_input_type}}" name="server" class="new-chatroom-server"
         placeholder="{{label_server}}"/>
     <input type="submit" name="join" value="{{label_join}}"/>

src/templates/roster.html

-<input style="display: none;" class="roster-filter" placeholder="{{placeholder}}">
-<select style="display: none;" class="filter-type">
-    <option value="contacts">{{label_contacts}}</option>
-    <option value="groups">{{label_groups}}</option>
-</select>
+<span class="roster-filter-group">
+    <input style="display: none;" class="roster-filter" placeholder="{{placeholder}}">
+    <select style="display: none;" class="filter-type">
+        <option value="contacts">{{label_contacts}}</option>
+        <option value="groups">{{label_groups}}</option>
+    </select>
+</span>