* add new option enable for include of spec
* fix to see the environment variable when parsing include
* add test for include with environment variable
* fix how to parse boolean value
* add spec about enable for include
* add Change Log
* fix the number of PR in changelog
* fix include test to make more clear
* fix test to focus enable option more
* fix english error
* fix to expand variable only one time
* add new test case by setting environment object as NO