UI: Clean up HTML a little.

src/main/resources/web/index.html

src/main/resources/web/tpl/flow-list-item.html

src/main/resources/web/tpl/flow-list.html

src/main/resources/web/tpl/header.html

src/main/resources/web/tpl/home.html

src/main/resources/web/tpl/host-list-item.html

src/main/resources/web/tpl/host-list.html

src/main/resources/web/tpl/host.html

src/main/resources/web/tpl/port-list-item.html

src/main/resources/web/tpl/port-list.html

src/main/resources/web/tpl/status.html

src/main/resources/web/tpl/switch-list-item.html

src/main/resources/web/tpl/switch-list.html

src/main/resources/web/tpl/switch.html

src/main/resources/web/tpl/topology.html

src/main/resources/web/tpl/vlan-list-item.html