Added output_magic to 

* Changed private_encoding to be the default behavior for the new  api. 
* Changed pipes.TaskContext so that it will magically convert  uplink.send() arguments to strings if private_encoding is enabled.
* Fixed submit so that it will put the hadoop task working directory in PYTHONPATH. Otherwise, cached module and packages will not be importable by the driver program.
* Rewrote the input_format example to use submit