Fixing LegendreWCS call method
Merge pull request #80 from shaileshahuja/Fixing-WCS-call-method

Fixing LegendreWCS call method
Adding metadata to Legendre and Chebyshev functions
Improving the FITS reader, now it conforms strictly to IRAF format. Added an IRAF combination class to hold multiple WCS as well as metadata for multispec format, and changed the fits reader to take in multiple WCS per spectra
Merge branch 'reader-IRAF-strict' of github.com:shaileshahuja/specutils into reader-IRAF-strict