Fixes project_out_vectors method.

- It also adds a convenient property `_jacobian` to be used by the `Simultaneous` family of `LK` algorithms for fitting `AAMs`.

In `Simultaneous` algorithms we require the following appearance `Jacobian`:

    appearance_jacobian = self.appearance_model._jacobian.T

and we require `appearance_jacobian` to be:

    (n_features x n_dims) x n_components

instead of the usual Menpo `Jacobian` shape:

    n_features  x  n_components  x  n_dims

For the time being, `_jacobian` is equal `components` on `PCAModel`. This is most probably a temporary thing due to the fact that all data used so far is real. If complex data is used, the same `PCAModel` class (or a subclass) could be used to perform `ComplexPCA` (Circular) but, in that case, the `Jacobian` would have a different form that would not be equal to the `components`.