JSONTokener(InputStream) violates rfc8259#section-8.1 (#739)

[michael-o]

Always use UTF-8 when an InputStream is passed.

This fixes #739.

[stleary]

What problem does this code solve?
Resolves a non-compliant part of the lib - JSON text should use UTF-8.

Risks
Low

Changes to the API?
No

Will this require a new release?
No

Should the documentation be updated?
N/A

Does it break the unit tests?
No, and no new tests were added.

Was any code refactored in this commit?
No

Review status
Approved

Starting 3-day comment window.

@michael-o Good catch