Features for %slurm and documentation.

[rcthomas]

Now there is %slurm slurm magic to control display and potentially other configurations. For example like

%slurm display raw
%slurm display pandas
%slurm display

With the default for display being pandas of course. This needs to be documented and fleshed out.

Also maybe just %slurm without any args should cough up the current configuration.