Update `roost_worker.rb'.

`roost_worker.rb' now sends a single notification for lunch, and a
single for dinner. Previously, it would send out both a meat and veg,
for lunch and dinner respectively.

Since it sends out more data, the bodies of the menu_items have been
removed.
Add random vegeterian options as well.

Previously, only random meat options were supported. This adds more
variety for vegeterians.

The body has also been removed from the vegeterian options. This is in
light of the new change (where both veg and meat options are pushed
together, so there's no space for the body).