Fix State::configure alias and implementation

[jvshahid]

I found out this error while I was investigating errors while running the active record test suite under JRuby. The error is:

NoMethodError: undefined method `merge' for #<JSON::Ext::Generator::State:0x53c20385>
    from /home/jvshahid/codez/jruby-pg/tmp_rails/activesupport/lib/active_support/json/encoding.rb:67:in `options_for'
    from /home/jvshahid/codez/jruby-pg/tmp_rails/activesupport/lib/active_support/json/encoding.rb:50:in `encode'
    from /home/jvshahid/codez/jruby-pg/tmp_rails/activesupport/lib/active_support/json/encoding.rb:82:in `check_for_circular_references'
    from /home/jvshahid/codez/jruby-pg/tmp_rails/activesupport/lib/active_support/json/encoding.rb:49:in `encode'
    from /home/jvshahid/codez/jruby-pg/tmp_rails/activesupport/lib/active_support/json/encoding.rb:34:in `encode'
    from /home/jvshahid/codez/jruby-pg/tmp_rails/activesupport/lib/active_support/core_ext/object/to_json.rb:16:in `to_json'
    from json/ext/GeneratorState.java:210:in `generate

It turns out that the configure method wasn't aliased properly in the Java version and when I tried to run the new test under MRI I found out that the configuration strings aren't stored with the null character so I fixed that as well.

This patch includes a test that covers both merge and configure as well as a fix for both implementations to make the test pass.

[jvshahid]

Ping, is there any update on this PR ?

[dwbutler]

It's strange, but even with the merge alias added, I'm still having the same issue. I've tested against both JSON 1.7.6 and JSON-master.

https://gist.github.com/4632270