Provide a Class instead of a static method

[rbecheras]

The aim is to be able to to for example:

var usersCtr = requrie('./users.ctrl')
var sequence = new ConnectSequence()

sequence.append(isAuthorized, usersCtrl.editProfile)

...
sequence.append(...)
...
sequence.run(req, res, next)

function isAuthorized (req) {
  return req.user.id = req.profile.id
}