Restore class method from_json, as event is no more an included class
Repair outputs/file test + add use of zcat command to cover LOGSTASH-997
Add clear_interval and flush_interval options for metrics filter
Add observation that intervals should be a multiple of 5s
Adds tests for metrics filter and fixes key collision

When using multiple instances of the metrics filter,
the keys collided, making the counters interfere with
each other.
Add metrics filter tests for clear and flush intervals
Merge pull request #545 from jbochi/master

Add clear_interval and flush_interval options for metrics filter
Merge pull request #633 from wiibaa/spec-output-file

Correct test case spec/output/file.rb
Add contributors and changes for recent pull requests.
Added make update
- improve conversion of oldlogstashjson (@source_host -> host, etc)
- use 'text' instead of 'line' (which is overwritten by Cabin at
loglevel debug)
Merge pull request #655 from logstash/logging-fix

- use 'text' instead of 'line' (which is overwritten by Cabin at
Merge pull request #654 from logstash/improve-oldlogstashjson

- improve conversion of oldlogstashjson (@source_host -> host, etc)
Merge git://github.com/logstash/logstash