Add IPv6 grok pattern.

Rename IP pattern to IPV4 and add new IP pattern that matches either IPV6 or
IPV4 patterns.

IPV6 regex swiped from http://forums.intermapper.com/viewtopic.php?t=452
outputs/riemann: make event tagging work again

As tags on outputs are now deprecated, we pass the tags set at input or
filter stage to Riemann events.

For the record, the idea is to pass along Logstash's events tags to the
Riemann events created, so that filtering *in Riemann* can be done based
on the tags set by Logstash.
outputs/riemann: minor cleanups

 - remove trailing whitespace
 - clarify how tags work + other small documentation updates
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 option to specify canned ACL in AWS S3 output configuration

    * Adds the option "canned_acl" which defaults to "private"
    * Breaks the previous behaviour where the canned ACL was hard-coded to "public_read".
      Which is a potential security problem, allowing everyone to access the file on S3.
Merge pull request #631 from mfournier/riemann-tags-issue

riemann plugin: make tagging work again
Merge pull request #637 from hduregger/cannedAcl

Add option to specify canned ACL in AWS S3 output configuration
Merge pull request #623 from bodgit/ipv6

Add IPv6 grok pattern.
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)
Added support to parse os name, major and minor