option to use multiple references in BLEU
option to use multiple references in BLEU

Conflicts:
	neuralmonkey/evaluators/bleu.py

juliakreutzer/bandit-neuralmonkey,juliakreutzer/bandit-neuralmonkey,ufal/neuralmonkey,juliakreutzer/bandit-neuralmonkey,juliakreutzer/bandit-neuralmonkey,ufal/neuralmonkey,ufal/neuralmonkey,juliakreutzer/bandit-neuralmonkey,ufal/neuralmonkey,ufal/neuralmonkey