use numpy.issubdtype to support numpy.scalar in roi_max_align_2d.py
use numpy.issubdtype to support numpy.scalar in roi_max_align_2d.py

chainer/chainer,niboshi/chainer,hvy/chainer,chainer/chainer,pfnet/chainer,chainer/chainer,chainer/chainer,wkentaro/chainer,wkentaro/chainer,niboshi/chainer,niboshi/chainer,wkentaro/chainer,hvy/chainer,wkentaro/chainer,niboshi/chainer,hvy/chainer,hvy/chainer