Proposed fix for #1167.

Fixes saving cubes with reserved attribute names to netCDF.
Added test for saving cube to netcdf with clashing reserved attribute.
shapeOfTheEarth of 3
Use getncattr when loading global attributes.

Avoid a situation where an attribute whose name clashes with a
netCDF4.Dataset attribute (e.g., dimensions) will end up with the
value of the netCDF4.Dataset attribute instead of the actual
attribute from the netCDF file.
Add a package init file for the cf tests.

Otherwise the tests aren't run!
Fix support for descending coordinate order.
Merge pull request #1326 from ajdawson/setncattr

Fix for netCDF4 reserved attribute names.
Latest CF names table
Latest v27
Merge pull request #1349 from rhattersley/concat-fix

Fix concatenate for descending coordinate order.
Merge pull request #1351 from bjlittle/cf-standard-name-table-upsdate

Latest CF names table
Product definition template 31.
Latest test data for Travis
Review actions
Merge branch 'v1.7.x'

* v1.7.x:
  Fix support for descending coordinate order.
  Add a package init file for the cf tests.
  Use getncattr when loading global attributes.
  Added test for saving cube to netcdf with clashing reserved attribute.
  Proposed fix for #1167.
Merge pull request #1350 from bjlittle/grib-pdt-31

Product definition template 31.
Merge pull request #1342 from bjlittle/grib2-ellipsoid-sote3

shapeOfTheEarth of 3
Product definition template 1.
Updated GRIB2 integration cml.
doc-string update.