Work done by @guyboertje and @ph
Since JRuby 1.7.25 is now EOL we are migrating Logstash to use JRuby 9k and JDK8 only,
Not much needed updating to make this work, its was mostly a drop in replacement from the previous version.
The major point was the change in the implementation of Time in JRuby, JRuby now use `java.time`
instead of joda time, this allow JRuby to have nanoseconds precision on time object.
remove unused load path
use either local core lib dir or logstash-core gem
include spec in logstash-core
do not include lib, spec and locales dirs in package root
environment bootstrapping in lib/bootstrap.rb
added comments
move pluginmanager out of logstash-core
kafla installation solved by pluginmanager refactor
refactor bootstrap code
refactor shell scripts to simplify and DRY, indirect rspec command to our ruby launcher
add bin/rspec
cut by half the bin/plugin and bin/rspec startup time
fix drip context
use printf instead of tr
updated Windows bin scripts
missing gemspec in gemspec
use gem instead of gemspec so our plugin manager can correctly install logstash-core
generate packages including locally built logstash-core gem
move jenkins developmnent dependencies into Gemfile, they do not belong in logstash-core
path leftover
clean help agent help usage message and remore rspec in available command
comments cosmetics
update Bundler dependency, all recent testing have been made with 1.9.4
updated .lock file with regard to updated Gemfile
cleanup gemspec, Gemfile and regen .lock file
added progress output
avoid dual require on version
closes#3096
