Use `shifu init -t xxx` to specify the algorithm in model config

[Liu-Delin]

I try to use WDL and it is uneasy to go through all the steps of shifu init/stats/norm/train, because I need to change lots of configuration in ModelConfig.json.

If we can use command like shifu init -t wdl to generate a model config with WDL configuration, it should be easier to use.

Related code:
https://github.com/ShifuML/shifu/blob/master/src/main/java/ml/shifu/shifu/container/obj/ModelConfig.java#L267-L285

shifu/src/main/java/ml/shifu/shifu/container/obj/ModelTrainConf.java

Line 531 in 2a3c459

public static Map<String, Object> createParamsByAlg(ALGORITHM alg, ModelTrainConf trainConf) {