Add support for ne3np4.pg2

[ekluzek]

We need support for ne3np4.pg2 resolution.

This relates to the CTSM issue:

ESCOMP/CTSM#3487

[ekluzek]

I pushed a branch tag that has a preliminary fix for this for the part needed by mksurfdata_esmf in CTSM.

ccs_config_cesm1.0.61_add_domain_ne3np4.pg2_1