Added directory for docs
spec out subcube
Make SpectralCube stokes-agnostic
Moved orient utilities to cube_utils
Make FITS loader deal with 3- and 4-d data
Fix 4-d cube reading
Fix WCS re-ordering
Fix FITS writing
Added TODO
Address comments by @keflavich
Merge pull request #17 from astrofrog/stokes-refactor

Stokes refactor
Added .travis.yml for testing
minor change
implemented 9ish actions
application along arbitrary axis
implementation of flattened slices
fixes to spectral cube definition
repr
add slices
add repr for cube