Bug fixes and enhancements.

Fixed toCamelCase to actually return camel case string.
Fixed task.prepare in both _.extend calls.
Fixed applyAsync, delayAsync and mapAsync with _.partial(callback, null)
for proper err/success callback standard.
Added task.mapAsync
Added task.map
Added comments for future task.starMap and task.chunks
Updated README

...for task.map and task.mapAsync
Updated package.json for new task functions.