[Seaside] SushiStore removed from Seaside

[Robert Hawley]

There is lots of mention and documentation about the sushi store on the
internet - yet when you persue it, a google search mainly recovers
irrelevant bits and pieces to do with Magma.

Add this to the confusions that arise through the shift to 2.8 and this
inconsistency on the web is not too good.

Given that the sushi example has been so well documented and was
consistently incorportated into earlier seaside versions, it would be good
to have that consistency continue and so have it available within the
current seaside examples and as a download.

There was some distaste for the example because it was from an earlier
version and did not fit with current practice - however, that would provide
justification for a rework in order to make the new practices clearer.

Has anyone done an updated version - and if so, can it please be included in
the seaside examples?