* replace boost::algorithm::ends_with with self define ends_with function

* remove BOOST macro in certain operators

* remove boost::lexical_cast

* add test for string_helper

* add more test case for string_helper

* modify join_string func and test case

* fix build_strategy_test failed bug

* remove string_helper_test from parallel_UT_rule.py

* fix save/load with unexpected value
* fix save and user interface
* add save sparse sharding to selected rows