add unit/integrted tests for dpc

I agree with this.

> On Dec 1, 2014, at 3:43 PM, Thomas A Caswell <notifications@github.com> wrote:
> 
> In skxray/dpc.py:
> 
> > +    phi_padding = np.fft.ifft2(c)
> > +
> > +    phi = phi_padding[(pad // 2) * rows : (pad // 2 + 1) * rows,
> > +                      (pad // 2) * cols : (pad // 2 + 1) * cols]
> > +    
> > +    phi = phi.real
> > +
> > +    return phi
> > +
> > +
> > +def dpc_runner(start_point, pixel_size, focus_to_det, rows, cols, dx, dy,
> > +               energy, roi, bad_pixels, solver, ref, image_sequence, padding=0,
> > +               w=0.5, scale=True):
> > +    """
> > +    Controller function to run the whole DPC.
> > +
> This is probably the function where the reference should go as this is the main user API into this functionality.
> 
> —
> Reply to this email directly or view it on GitHub <https://github.com/Nikea/scikit-xray/pull/177/files#r21117818>.
> 

--
Best Regards,

  Cheng Chang 
  Computer Engineering, Stony Brook University
  Computer Science Group, Computational Science Center, Brookhaven National Laboratory
  Tel：(001) 631-885-4922