changes to fill in all of the BlockLocations information for each file.

[childsb]

trafficstars

This fix adds fields to the BlockLocation metadata for each file.

[jayunit100]

Can you add a unit test for this ?

[jayunit100]

(although obviously you cannot unit test block locality in the JVM) - but a unit test which at least tests that some of the logic of the code youve added here is working .