Added in the ability to remove null values from an active data provider series

@miloschuman Just checked on why this doesn't merge smoothly, looks like there are conflicts between our demo info in the header.  Sadly I'm still using a short fork off of your v3.0.10 tag, as we haven't yet updated to Highcharts v4.  Do you need me to rebase this branch off of your master branch or can you do that?