patch jruby utf-8 method naming, fixes #1507
Use `JRUBY_VERSION` instead of `RUBY_VERSION`.
Merge pull request #1508 from padrino/1507-fix-jruby-utf

patch jruby utf-8 method naming, fixes #1507
Remove charset from json mimetype, fixes compatibility with sinatra edge.

Set :add_charset option for old sinatra version.

Replace `unless~else` with `if~else`, remove an array.
Merge pull request #1505 from padrino/remove-charset-from-json

Remove charset from json mimetype, fixes compatibility with sinatra edge.
Don't create rspec rake task for each folder
Fix tests to check for new spec.rake syntax