[FIX] Travis error fixed, _ importation missing
[MOD] <mrp_product_variants> and <mrp_product_variants_types>
[MOD] Fixing errors
Merge branch '8.0-mrp_variants' of github.com:oihane/odoomrp-wip into 8.0-mrp_variants

Conflicts:
	mrp_product_variants/models/mrp.py
[MOD] Fixing errors