Revert the ctc loss to 2.1.2 and fix the bug of export model

fix the bug of import ctc decoder

[BUGFIX] Fix wget https with --no-check-certificate

compute cmvn before build vocab

update the wget script for openfst

[WIP] ctc loss api debug

multi workers for valid dataloader

argparse load conf from file

format code

rm useless swig dir

refactor raw ctc decoder into ctcdecoder, new join ctc/att decoder

using simple test for multi decode type, and using gpu

update the benchmark

update timit result

update timit result

resume not increase epoch and step, before_train do it

fix ctc loss not convergence