README: Add notes on CDN use via RawGit/MaxCDN
Selector: Remove unused 'dgrid-select-all' class

This wasn't being reliably added/removed in all cases, but no styles or
functionality depend on it, so it's probably not worth the code to fix.
Fix getChildren in a Tree test store and remove pointless root filter
Ensure that OnDemandList aways removes an even number of rows
Pagination: update total to the data length
remove the dgrid-prune event