TRIAL: Fits multispec

First trial with @wkerzendorf at combining `read_IRAF_spec` into a fits reader (using actual wcs).  The below worked! (only for legende polynomials):
```
In [1]: from specutils.io import read_fits

In [2]: m = read_fits.read_fits_multispec('K09418619_2013-10-18_02h19m17s_cb.spec.fits')

In [3]: import matplotlib.pylab as plt

In [4]: plt.ion()

In [5]: for m1 in m: plt.plot(m1[0].wavelength, m1[0].flux)
```