codec/line: do charset conversion on flush

Add tests to verify line codec does charset conversion on flush.

Fixes #1520
Remove the "how to get help" banner because nobody reads it.

There's several indications that folks don't actually read this banner
when unexpected errors occur. If nobody's reading it, then it's just
wasting space in the output.

I would cite references, but will not because there's no need to shame
anyone.

Fixes #1442
gem bundling refactor

update jruby jar to 1.7.15

pinned i18n dependency and cosmetic cleanups

new generated Gemfile lock

refactor gem bundling using stadalone setup & use standard Gemfile with gemspec

update to jruby 1.7.16 and remove jar-dependencies, bouncy-castle-java, jruby-openssl from gemspec

get ready for future plugins mechanism
allow user@hostname in commonapache log
Closes #1500 #1736
ElasticSearch output plugin to support multiple hosts and enhance stability. (by Hao Chen)

1. Make elasticSearch output plugin to support mutiple hosts and round robin balance, which will help a lot to balance the resource and performance of whole elasticsearch cluster.
2. Improve stability by handling exception and retry with left servers while flushing bulk, which will reduce the possibility of data loss largely.
Remove retry logic and just try to install template until successing as the first time
NodeClient Support hosts in array
#1791: Enhance switching ES client logs
#1791: Add haoch to CONTRIBUTOR
#1791: Add unitest for elasticsearch node client to support both string and array which helps a lot for elasticsearch clients balance
#1791: Fix comments
#1791: Handle exception while configure `host` is null
Added debug check before logging
Closes #1791