MAINT: Slight refactor.

Moves numpy version determination out of the loop which was causing a
significant impact on performance due to namedtuple class construction.
Switch to simultaneous conda install.
Merge pull request #1335 from cpelley/regrid_refactor

MAINT: Slight refactor.
Merge remote-tracking branch 'upstream/v1.7.x' into merge_master_17x

Conflicts:
	conda-requirements.txt
Proposed fix for #1167.

Fixes saving cubes with reserved attribute names to netCDF.
Added test for saving cube to netcdf with clashing reserved attribute.
Use array's copy method instead of copy.copy().
Merge pull request #1336 from ajdawson/cube-copy-mask-maint

Use array's copy method instead of copy.copy().
Merge pull request #1340 from cpelley/merge_master_17x

Merge of 1.7.x into master
shapeOfTheEarth of 3
Quiet conda setup.
Quiet Iris build/install
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!
Merge pull request #1344 from SciTools/v1.7.x

V1.7.x
Merge pull request #1343 from rhattersley/quiet

Quiet setup/build/install in Travis-CI
Remove last usage of duplicate test data file.

This means the iris-test-data tarball can be a little smaller.

Closes #1244.
Merge pull request #1346 from QuLogic/remove-duplicate-test-file

Remove last usage of duplicate test data file.
Fix support for descending coordinate order.
Merge pull request #1326 from ajdawson/setncattr

Fix for netCDF4 reserved attribute names.