License-sh

Exit code fixed for `-t` option

Npm/Yarn license parsing improved

1. User can now ignore packages what either has no license or he/she is sure these packages are not a threat.


"ignored_packages": {
"python_pipenv": [
"PyInquirer",
"setuptools"
],
"npm": [],
"maven": [],
"yarn": []
}


2. User can now run this program as `python3 -m license_sh`