Add encoding cache and lazy-train mechanism (#50)

* Add new config about knowledge distillation for query binary classifier

* remove inferenced result in knowledge distillation for query binary classifier

* Add AUC.py in tools folder

* Add test_data_path into conf_kdqbc_bilstmattn_cnn.json

* Modify AUC.py

* Rename AUC.py into calculate_AUC.py

* Modify test&calculate AUC commands for Knowledge Distillation for Query Binary Classifier

* Add cpu_thread_num parameter in conf.training_params

* Rename cpu_thread_num into cpu_num_workers

* update comments in ModelConf.py

* Add cup_num_workers in model_zoo/advanced/conf.json

* Add the description of cpu_num_workers in Tutorial.md

* Update inference speed of compressed model

* Add ProcessorsScheduler Class

* Add license in ProcessorScheduler.py

* use lazy loading instead of one-off loading

* Remove Debug Info in problem.py

* use open instead of codecs.open

* update the inference of build dictionary for classification

* add md5 function in common_utils.py

* add merge_encode_* function

* update typo

* update typo

* reorg the logical flow in train.py

* remove dummy comments in problem.py

* add encoding cache mechanism

* add lazy-load mechanism for training phase

* enumerate problem types in problem.py

* remove data_encoding.py

* add lazy load train logic

* Modify comment and remove debug code

* Judge if test_path exists

* fix parameter missing when use char embedding

* merge master

* add file_column_num in problem.py

* merge add_encoding_cache branch

* add SST-2 in .gitignore

* merge master

* use steps_per_validation instead of valid_times_per_epoch

* Fix Learning Rate decay logic bug

* add log of calculating md5 of training data

* fix multi-gpu char_emb OOM problem & add char leval fix_lengths

* Modify batch_num_to_show_results in multi-gpu

* Modify batch_num_to_show_results

* delete deepcopy in get_batches

* add new parameters chunk_size and max_building_lines in conf and update tutorials

Modify sequence labeling tutorial (#69)

* add sequence labeling in tutorial

* add tag scheme convert script

* add paper link

* modify sequence labeling tutorial

* modify senquence labeling tutorial

add language supported for README (#33)

add installation and quick start in readme.md