fix vars assignation in Trainer::load_state
fix vars assignation in Trainer::load_state

clab/dynet,danielhers/dynet,clab/dynet,danielhers/dynet,danielhers/dynet,shuheik/dynet,clab/dynet,clab/dynet,shuheik/dynet,clab/dynet,clab/cnn,clab/dynet,danielhers/dynet,clab/cnn,shuheik/dynet,shuheik/dynet,clab/dynet,shuheik/dynet,danielhers/dynet,clab/cnn,shuheik/dynet,danielhers/dynet,shuheik/dynet,danielhers/dynet