…protocol

This change update the CreatePartitions request and response api objects
to use automated protocol. The change involved updating all client code
to use the newly updated CreatePartitionsRequest and
CreatePartitionsResponse classes.

Updated relevant tests. All tests pass.

The commit contain three changes:

1. Rename "integers" variable to "brokerIds"
2. Take out "()" from method calls as per coding convention
3. Refactor AdminManager::createPartitions to get rid of chained maps.

Empty reassignment was treated as error condition before, filtering it
out now ignores this case and creates new partiton using default
assignment.

This change removes that filter, so that the error condition is
triggered again and `InvalidReplicaAssignmentException` gets thrown.