Update queries

[ayende]

So we can support "migration" style queries like:

from doc in docs
where doc.type == "post"
select new
{
type = doc.type,
content = doc.content,
posted_at = doc.posted_at,
categories = new [] { doc.category }
}

Should run at the server side, not client side, and the output overwrite the current document.

[ayende]

Not going to implement this, it is pretty easy to handle this at the client API level