web: fix the filterpanel column width

Set flex = 1 on the column so it auto expands to take up the
entire available width.

deluge/ui/web/js/deluge-all/FilterPanel.js

@@ -77,7 +77,8 @@ Ext.define('Deluge.FilterPanel', {
                 id: 'filter',
                 sortable: false,
                 tpl: tpl,
-                dataIndex: 'filter'
+                dataIndex: 'filter',
+                flex: 1
             }]
         });
         this.relayEvents(this.grid, ['selectionchange']);