Use the right charset while decoding response in imap nio client

[davis-thomas]

Description

When response from IMAP servers is decoded in IMAP NIO client, not the right character set is being used. This cause array index out of bound exceptions while parsing the IMAPResponse using default sun libraries. The fix is to use the right charset so the decoding responses is not lossy.

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Major release (change is NOT backward compatible with prior release)

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[fansu]

Could you also change parent pom.xml, core/pom.xml, README.md to be 5.0.2?