Support JRuby 10

[meineerde]

JRuby 10.0.0.0 was released today. It would be great of you could add support for it.

Thus would necessarily include support at least for the following version specifiers

• jruby-10
• jruby-10.0

The jruby specifier may also need to be updated to refer to jruby-10.0.0.0

I'd assume that you can generally re-use the setup logic which is currently applied for jruby-head for this.

[eregon]

See rbenv/ruby-build#2520 (comment)