specutils.Spectrum1D refuses a Pandas Series as input

I tried adapting the specutils demo notebook for my own spectra. The input spectrum is in a pandas dataframe, which specutils.Spectrum1D() refuses as follows:

----> 1 s1723_spec = specutils.Spectrum1D(spectral_axis = df_s1723['wave'] * u.AA, flux=df_s1723['fnu'] * u.Unit('Jansky'))

~/anaconda3/envs/astroconda/lib/python3.6/site-packages/specutils/spectra/spectrum1d.py in __init__(self, flux, spectral_axis, wcs, velocity_convention, rest_value, redshift, radial_velocity, bin_specification, **kwargs)
97 if flux is not None:
98 if not isinstance(flux, u.Quantity):
---> 99 raise ValueError("Flux must be a `Quantity` object.")
100 elif flux.isscalar:
101 flux = u.Quantity([flux])

ValueError: Flux must be a `Quantity` object.

The kludgy workaround is to put .values after each Series:
s1723_spec = specutils.Spectrum1D(spectral_axis = df_s1723['wave'].values * u.AA, flux=df_s1723['fnu'].values * u.Unit('Jansky'))

A better solution would be for astropy to gracefully accept a pandas Series. (And maybe even a pandas dataframe? Hey, I can dream.)

Start at specutils/spectra/spectrum1d.py, particularly the Spectrum1D constructor and its flux validation. Check how pandas Series values interact with Quantity inputs, then verify that the shown Series-based call works without .values while retaining the supplied units; dataframe support is only suggested, not specified.

Written by the indexing model from the issue text.