add test to sprintf to cover metadata support

Fixes #2149
install default plugins via bundler

Fixes #2107
handle vendored/nonvendored ruby and reset env vars

Fixes #2107
fix gem_home setting in environment.rb

Fixes #2107
codec#on_event api change

Fixes #2140
Avoid static file corruption (small.png) on Windows

When using `logstash web` on Windows the Kibana Logo on the dashboard is broken. This is because it will return small.png with 479 instead of 480 bytes (removing a 0x0d).

Fixes #1796
fix doc inconsistency about the versions in the getting started guide

Fixes #2109
clean up some reference to logstash.net in benefit of the es site

Fixes #2109
fix the release notes ascii docs style

Fixes #2109
add a reference to the plugins page within the logstash getting started tutorial

Fixes #2109