Cypher sees updates while reading

Because we try hard to make Cypher lazy, we can today run into the situation where a query that both reads and updates, can see it's own updates while reading.

This is an problematic query today:

    START n=node(*)
    CREATE ()

This query will see the newly added nodes while it's fetching all the nodes from the database, and will end up in a never ending loop.

This pull request solves this by making the reading eager before doing updates.