fixed load and save to work in python 3 as well, considering the change to bytes()
fixed load and save to work in python 3 as well, considering the change to bytes()


Former-commit-id: ada442ae70c1aff157127dc76c94f38bfcf089e5
clab/dynet,danielhers/dynet,chunyang-wen/dynet,chunyang-wen/dynet,danielhers/dynet,danielhers/dynet,xunzhang/dynet,clab/cnn,shuheik/dynet,shuheik/dynet,clab/dynet,chunyang-wen/dynet,danielhers/dynet,clab/dynet,chunyang-wen/dynet,clab/dynet,shuheik/dynet,xunzhang/dynet,shuheik/dynet,clab/dynet,clab/cnn,shuheik/dynet,xunzhang/dynet,clab/dynet,danielhers/dynet,danielhers/dynet,clab/dynet,danielhers/dynet,shuheik/dynet,shuheik/dynet,clab/cnn,xunzhang/dynet