External Sorting does not work with Sorting

[JLLeitschuh]

Problem

When grouping with server sorting enabled the data does not sort first.

Steps to reproduce:

1. Try to group by name.

http://plnkr.co/edit/Fa9TmlYZTIjPqu5xOThU?p=preview

Desired result

When grouping the server sort should be triggered when grouping.

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Is this as intended or is it a bug?

[JLLeitschuh]

I'm pretty sure that this could be solved by adding this line:

grid.api.core.raise.sortChanged(grid, grid.getColumnSorting());

Here:
https://github.com/angular-ui/ui-grid/blob/master/src/features/grouping/js/grouping.js#L684