fix CASA .image reading: should not assume 3d by default, since usually
stored as 4d
need to pass CASA's units into SpectralCube
(also, should check for importerror with aplpy quicklooks)
fix a merge mistake in spectral quicklook
updated CHANGES
add 'save' to quicklooks
with_mask checks for broadcastable, not equal shape
clean up tests of broadcastability
bugfix: with_mask should be usable when no `_mask` is defined
update apt-get listings (fixes graphviz install issue)
Don't write strings in FITS format--just keep them as the default. yt will understand.
Merge commit '0816688c89bff950b7f66a8ed895cdfd1707d7e9'

* commit '0816688c89bff950b7f66a8ed895cdfd1707d7e9': (28 commits)
  Don't write strings in FITS format--just keep them as the default. yt will understand.
  update apt-get listings (fixes graphviz install issue)
  bugfix: with_mask should be usable when no `_mask` is defined
  clean up tests of broadcastability
  with_mask checks for broadcastable, not equal shape
  add 'save' to quicklooks
  updated CHANGES
  Revert "We should just keep the strings in the standard AstroPy format, because yt knows about those"
  We should just keep the strings in the standard AstroPy format, because yt knows about those
  fix a merge mistake in spectral quicklook
  need to pass CASA's units into SpectralCube (also, should check for importerror with aplpy quicklooks)
  fix CASA .image reading: should not assume 3d by default, since usually stored as 4d
  Fixing this
  These tests won't pass completely until yt 3.0.1 is installed in Anaconda.
  Most of these tests pass now, but there's a nasty bug that I need to track down.
  Adding assert_array_equal for integer ndarrays
  Some unit tests for yt
  Replacing pf with ds to reflect yt 3.0
  Only need to test 1.7
  Only allow yt tests for recent numpy versions
  ...