Bug fixes.

task.applyAsync omitted options raised error.
task.delay now has optional options.
client.close no longer requires a callback.
Revert "Bug fixes."

This reverts commit 01662d8a634e6b2d93a0ea7b0e4819ee556dfd91.
Revert "Revert "Bug fixes.""

This reverts commit c3a53f882e5de5dd70b84611fc20182d08955ce6.