Feature Request: License Scanner compares against allowed licenses

**Issue:** license-scanner does not inform if there is a mismatch of licenses, it only returns the list of licenses.

**Discussion:** CI/CD implementation would benefit form license comparisons.

**Recommendation:** Implement a flag which would cause the std.out return true if all scanned licenses are on the whitelist, and false for otherwise.

### Use Case
As a CI/CD pipeline administrator, I can provide license-scanner a list of accepted licenses, and if there is a mismatch return false otherwise return true.