Update server outline view cells in each node

We use nested if statements when we update each NSTableCellView in the
server outline view. We have already moved a lot of code that required
such if statements to the node itself, and we can move this to.

Implement a method for each column and pass it the view, which it is
responsible for updating.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>