@message was missing in event, added 'Message' field to @message.
Updated comment on metric parameter

Fixed comment where example metric was:

[ "%{@source_host}/uptime", %{uptime_1m} " ]

This syntax will cause an error everytime. Updated to:

[ "%{@source_host}/uptime", "%{uptime_1m}" ]
Merge pull request #457 from eravenelle/patch-1

Updated comment on metric parameter for graphite output
Prep for multiruby support (targeting rbx)
- fix variable scoping
- prep for rbx/mri support
- only do jruby patches on jruby
- Fix homedir; was a remnant of a past life being in an rpm spec.
- comment out a print
- add sample sysconfig
- only do the File jar caching patch in JRuby
- don't emit gem list
- set GEM_HOME and GEM_PATH so gembag installs to the right place
  (for proper MRI/rbx support)
- only give notice about plugin status once per plugin
  Verified by running the test suite and not having a sea of
  "experimental plugin" warnings for the same thing repeatedly.
- make the end of the log profiler more obvious (style)
- make 'target' an absolute path otherwise ruby 2.0.0+rubygems 2.x
  refuses to install things. Cute :(
- Disable doc generation on rubygems 2
- Try to set GEM_HOME/GEM_PATH early on in the process.
- make RUBYVER tunable for ruby 2.0, not that it works well yet.
- fix backwards compat
- update readme
LOGSTASH-1003 LOGSTASH-1038 fixing both issues in one commit because the rabbitmq input is functionally broken until both are fixed