feat(instances): the VM list filters by state, and a host's name finds its VMs

The list gets a state selector beside the search box. The search now
matches plain text in any case (a '(' no longer breaks it), and in the
grouped list a host's name shows all of its VMs while a host row shows
only while one of its VMs does. The filter moves to
static/js/instance_filter.js with a Node test; the other lists keep
filter-table.js. Collapsing a host now sets a class on its table body
instead of each row's display, so a collapsed host and the filter no
longer undo each other.

static/css/webvirtcloud.css

@@ -53,6 +53,10 @@ body {
     height: 350px;
 }
 
+.host-collapsed tr[host] {
+    display: none;
+}
+
 .search {
     margin: 5px;
 }