BRANCHES instead of RANCHES

[DiegoEPaez]

In cls_hrnet_w18_small_v2_sgd_lr5e-2_wd1e-4_bs32_x100.yaml STAGE1 configuration should read NUM_BRANCHES instead of NUM_RANCHES. In fact this doesn't affect in anything the code since .make_stage instead called for stage1; however, just to be consistent it be good to change it.