* add lod_tensor util and modify pybind
* refind pybind LoDTensor API and modify LoDTensor and DataFeeder test
* fix test error
* fix detection map op test
* fix reorder_lod_tensor test
* fix seq_concat_op
* fix chunk evel op test
* fix target assign op
* fix warp ctc op
* address comments step 1: reverse reset_lod op
* step 2: modify op test
* add warning message
* remove has_valid_lod
* add back has_valid_lod
* address comments
* add exception catching trial
* add lod_tensor utility python module
* add lod_tensor test code
* add more lod tensor tests
* modify word2vec example code using new api
* add comment
minqiyang
Kexin Zhao
yuyang18
Kexin Zhao