Make sure ngGridEventStartCellEdit event is also emitted, so anyone can listen for it (instead of only emitting the endCellEdit event)

Why?

Because this is an easy way to store the current values on cell edit start, and then only saving them back to the server if something actually has changed.

I am not the first one with this requirement as can be seen here: https://groups.google.com/forum/#!topic/angular/2Vdvrm_BL6Q

and I gues I won't be the last, so I guess this is a sane addition.