In order to minimize ajax requests, I implemented isComplete property,
which can be used to check if record is fetched from the API or if it
was just partially loaded (for example by pusher event). This is nice in
terms of requests reduction, but caries risk of showing incomplete data.
This commit fixes this situation by saving which attributes were
provided on "incomplete" load and triggering refresh when any unknown
attribute is tried to be fetched.
The implementation is really simple and will probably need refactoring,
but I would like to test it in the wild before putting much more time
into it.
