Upgrade jruby
Update JRuby auto-installer in bin/logstash to use JRuby 1.7.5
Merge pull request #703 from logstash/upgrade-jruby

Upgrade jruby to 1.7.5
Merge pull request #721 from untergeek/master

Update JRuby auto-installer in bin/logstash to use JRuby 1.7.5
Updated JRuby URL for downloading 1.7.5
Merge pull request #722 from untergeek/master

Updated JRuby URL for downloading 1.7.5
- remove old junk
Merge pull request #723 from logstash/remove-unused-build-stuff

- remove old junk