Chainer utils use deprecated methods

[massongit]

(Related to #7)
These methods use deprecated methods when using Chainer v1.24.0:

deep-crf/deepcrf/util_chainer.py

Lines 44 to 49 in ee2880c

	def my_cuda_get_device(cuda, device_id):
	if version < '2.0':
	cuda.get_device(device_id).use()
	else:
	# v2.0
	cuda.get_device_from_id(device_id).use()

deep-crf/deepcrf/util_chainer.py

Lines 52 to 57 in ee2880c

	def my_cleargrads(net):
	if version < '2.0':
	net.zerograds()
	else:
	# v2.0
	net.cleargrads()