cleaned up dimarray.geo.crs.py
fix crs.py bugs and added tests
- add new dataset for testing polar stereo transform (success for coords)
- now transform works on 3-D array
- add rollaxis to DimArray
added __ne__ to dimarraycls
added tests, simplified crs.py
added RotatedPoles
by default copy grid_mapping parameters when reading netCDF file
and same when writing netCDF
removed DimArray naming when inserted in a Dataset
==> cleaner
rename write_grid_mapping to share_grid_mapping
added warnings when binary op with two grid mappings
bug fixes
Sort globbed files list before reading
renamed transform into projection
- important update: new internal handling of metadata
- DimArray, Axes, Dataset are subclass from MetadataBase
_metadata descriptor is done in MetadataBase
- fine control via class attributes __metadata_exclude__,
  and __metadata_include__
- new methods set_metadata, get_metadata, del_metadata
    to access single elements instead of the bulk
    _metadata's copy
    This should be used only for the rare cases of conflict.
    Standard setattr, getattr access is preferred (and faster)
do not initialize axes if an Axes object is passed
merge master
- updated docstring and examples with sorted netCDF files when reading
  with regular expression.
avoid the test np.asarray for lists as it takes a lot of time
bad fix
fix to speed up Axes initialization
Merge branch 'master' into geo