preserve the spectral units when creating an output header
add tests
Merge pull request #154 from keflavich/preserve_spectral_unit

Preserve the spectral units when creating an output header
preserving units: most of this work was already done and just wasn't
passed to header.  Added unit preservation (based on header) to __init__
now
fix bug + regression test
basic implementation of 1D *spectral* slices (WCS still has trouble with
non-spectral 1D slices)
fix a call to _new_cube_with and add a .value property to return a
unitless copy of self
implement @ChrisBeaumont's comments
Merge pull request #156 from keflavich/preserve_float_bugfix

Minor bugfix regarding nansum
Merge pull request #155 from keflavich/preserve_unit_2

Preserve the spectral units when creating an output header: rd. 2 - refactor!
REMOVE np.asarray: it does bad things to Quantities!
whitespace
asarray for value.ndim!  THAT's how you do it... riiight.
Merge pull request #157 from keflavich/slice_1d

Allow 1D Spectral Slices
Updated package template to v0.4.1 (includes update of astropy-helpers to v0.4.3)
Merge pull request #158 from astrofrog/update-template-0.4.1

Updated package template to v0.4.1 (includes update of astropy-helpers to v0.4.3)
first attempt at a to_glue machine.  Required fixing some bugs in
__getitem__ but that's no problem
the glue_app becomes part of the cube now so that subsequent calls add
the dataset to an existing session
allow a glue application to be specified.  add docstrings
attempt to accept updates of data collections