Hooks now take a list of parameters.

Instead of a map. Map was overly complicated for not much.
And now we can pass the topology parameters to the hook
(will do that in another change).
Renaming functions to be clearer.
Merge branch 'master' into replication
Adding support for unreachable data center.

With a unit test that showed me whta still needed to be done.
Add make target to run unit tests with race detection.
improved vttablet error annotations
annotate balancer errors
pushed annnotation to getEndPoints
Merge branch 'master' into barnacle