master/www: Add the graph name on top of images

As twinings216 reported in ticket #1349 :

    It's very convenient to use ctrl-f to find a graph in the browser. This
    depends on the textual titles of the graphs being present on the page,
    which was there in previous versions of munin, but not in the current
    version. This would add it back.

Closes: #1349
Merge branch 'ticket-1349' into devel

Conflicts:
	master/www/munin-nodeview.tmpl