add copyright

[Alanscut]

2 files(JSONException.java and JSONString.java) missing copyright, added them.

[stleary]

What problem does this code solve?
Doc change only: add copyright notice to 2 files.

Risks
None

Changes to the API?
No

Will this require a new release?
No

Should the documentation be updated?
No

Does it break the unit tests?
No

Was any code refactored in this commit?
No

Review status
ACCEPTED - No comment window needed.