fix encode (output) for oldlogstashjson codec.

It was referencing the obj variable which didn't exist
[elasticsearch_river][Fix] use mq.publish_serialized instead of receive_raw

receive_raw is no longer available in RabbitMQ.

elasticsearch_river throw the exception "undefined method `receive_raw'"

This commit fix issues 1298 and 1384
Write a failing test when prefix & include/exclude keys are used together
Fix a bug where field goes missing if include/exclude is used with prefix
Update grok-patterns

Add LOGLEVEL pattern "ALERT"
- deprecate message as was intended in 1.2.0, but I forgot.
(LOGSTASH-1413)
Fixes LOGSTASH-1328
- Compile capture processing to ruby code to avoid asking questions
  about startup-time configuration every time there's an event.

  This has a measured 6.3x perf improvement in grok filter performance.

  It passes *almost* all the tests (66 examples, 4 failures). Each
  failure is related to what I think is an uncommon edge case or
  a feature that is going away eventually. The broken tests will be
  fixed eventually.
- restore int/float field value pattern matching (converts to string
before running grok match; same as we did before)
- add a comment describing why we invoke .to_s
- add support for keep_empty_captures
- disable one test that has broken behavior (edge case, will resolve
later)
- work around inadequate support in LogStash::Event#include? to keep the
test passing correctly
Merge pull request #681 from logstash/grok-compile-capture-handling

- Compile capture processing to ruby code to avoid asking questions
Make 'if "something" not in [nonexistent] { ... }' succeed

My argument is checking for the absence of a value in a field that doesn't
exist should return true, currently it is false.

This fixes the case where an event which has never been tagged now works with
this logic:

    grok {
      ...
    }
    if "_grokparsefailure" not in [tags] {
      ...
    }
Fix fail() invocation if no config file is given.
Small enhancements to netflow codec

- Add configurable target field for netflow fields, defaults to "netflow"
- Add configurable filter to restrict which versions to accept
Stick to rufus-scheduler 2.0.x versions.

Unbreaks tests as seen in
https://travis-ci.org/logstash/logstash/jobs/12047597.
Make ES index requests synchronous. Prior to this, I had incorrectly
assumed that elasticsearch acting as a client had a fixed-size thread
pool to limit the number of active bulk index requests. This now
executes bulk index requests one at a time.
Unbreak #to_epoch method in datadog output plugin. (LOGSTASH-1427)

The event timestamp might already be a Time object.
Use latest kibana for the flatjar. (LOGSTASH-1416)
Merge pull request #678 from jippi/patch-1

Fixes LOGSTASH-1328