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
Merge pull request #1340 from cpelley/merge_master_17x

Merge of 1.7.x into master