Make KSC insert licenses comments and metadata into the generated files
It is a common practice to insert a piece of license into some files. Especially into GPL ones. KSC may
1 insert this pieces into generated files (there should be a pref to make it not to do that)
2 insert metadata in machine-readable way, for example python ```__license__```
3 insert a short comment

Do do this we need the following info about each license in a machine-readable way:
 * spdx identifier as a key
 * the text of short license notice to insert into a generated file
 * a short summary of the license like in tldregal (```you may```, ```you must```, ```you cannot```) or [GitHub Licenses API](https://developer.github.com/v3/licenses/) .
The proposed format to store this info is, of course, JSON (tldrlegal exports data in JSON). Or you can use yaml.