python 3 compatiblity --- filenames, bytes vs unicode
python 3 compatiblity --- filenames, bytes vs unicode


Former-commit-id: d718ec980529ed02174e87096efac6bc6d698910
shuheik/dynet,danielhers/dynet,chunyang-wen/dynet,chunyang-wen/dynet,danielhers/dynet,danielhers/dynet,clab/dynet,clab/dynet,clab/cnn,shuheik/dynet,shuheik/dynet,clab/dynet,shuheik/dynet,xunzhang/dynet,shuheik/dynet,xunzhang/dynet,clab/dynet,clab/dynet,chunyang-wen/dynet,shuheik/dynet,xunzhang/dynet,clab/dynet,danielhers/dynet,danielhers/dynet,clab/cnn,danielhers/dynet,danielhers/dynet,clab/dynet,chunyang-wen/dynet,clab/cnn,xunzhang/dynet,shuheik/dynet