Needed this line
Cleaning up documentation
Followed @astrofrog's suggestion and made these methods take the spectral_cube argument
Only allow yt tests for recent numpy versions
Only need to test 1.7
Fixing this
split out yt tests
fix yt test setup
make world2yt and yt2world private functions
whitespace/pep8
add a link to the yt docs
skip failing test: tests pass!
use StrictVersion for all yt version comparisons
Merge branch 'jzuhone_yt_rebase'.  Closes #90
fix test: yt_version needs to be defined even if yt can't be imported
to_yt returns a YtCube object
pep8 -> package naming convention
fix tests: methods of correct objects
one more excess spectral_factor removed
use zero-indexed coordinates in yt2world/world2yt
allow 0 or 1 indexing in yt2world and back.  Clean their docs a little