example app doesn't respect user account data

[iainkirkpatrick]

currently, whoever is logged in can see all dogs that have been created - the problem is a 'dog' has no concept of an 'owner' (an 'agentId').

remedy this by adding an 'agentId' column to the dogs table, passing in the current 'userId' on creation of a dog, and only querying the database for dogs belonging to the current user (and locking down the service to prevent retrieval of other users dogs)