2.9.0.rc1

This is a second release candidate for the upcoming 2.9.0 release which primarily improves TLS certificate and private key handling in various environments. The following notable tickets have been resolved:

• RUBY-1822 Support providing certificate chains as client certificates
• RUBY-1823 Support adding multiple CA certificates
• RUBY-1830 Fix TLS connections configured via URI options in JRuby

We expect to release 2.9.0 final in about 1-2 weeks.