add simple support for "templated" dashboards

* apply_all now supports a default value
* leverage that to show which values to fill in
* for an example, include the new server-basics dashboard
deal better with nulls in flot graphs

flot doesn't treat null values very well.
tswidget code has to remove them but if you use multiple targets
and one of them has a lot of nulls (and hence removed datapoints)
the graph display will break, so you have to use drawNullAsZero to
avoid that