Allow raw data to appear in tasks, change interface

[dfenster]

It would be nice to be able to do something like

flow.tasks = {
  file_data: new Task(fs.readFile, 'data1.txt'),
  file_data2: new Task(fs.readFile, flow.tasks.file_data)
};
flow.execute(function(err, results){
});

as an alternative to

flow.tasks = {
  file_data: new Task(fs.readFile, 'file_name'),
  file_data2: new Task(fs.readFile, 'file_data')
};
flow.execute({
  file_name: 'data1.txt'
}, function(err, results){
});

when proxies are usable in mainstream node.js