Out of order execution when mixing joins and fits.

[kevinswiber]

Example:

var pipeworks = require('pipeworks');

var a = pipeworks()
  .fit(function(next) {
    console.log('a');
    next();
  });

var b = pipeworks()
  .fit(function(next) {
    console.log('b');
    next();
  });

var c = function(next) {
    console.log('c');
    next();
};

var d = pipeworks()
  .fit(function(next) {
    console.log('d');
    next();
  });

a.join(b).fit(c).join(d).flow();

// Output:
// a
// c
// b
// d