*  fix mkdir conflict

*  fix load/save lookup tables

 test=develop

* add lookup_table_utils

* fix load optimize vars on pserver

* delete lookup table utils

* fix save and load lookup tables

* fix load optimizer var

* fix load optimizer var, test=develop

* fix python 3 style, test=develop

* move lookup_table_utils to contrib utils

* add hdfs utils

* add hdfs utils

* test=develop

* update hdfs utils and add demo

* fix multi_download return local files

* test=develop

* add sync multi upload, test=develop