Add jmx plugin

Description of this plugin.
This input scan a folder, every <polling_frequency>, containing some
json configuration describing jvms to monitor with attributes to
retrieve.
Then a pool of threads, reading those configurations, retrieve metrics
and create the event.

The configuration:
On the logstash configuration you have to set the polling frequency,
the number of thread use to poll metrics and a path where are stored
json files containing the configuration per jvm of metrics to retrieve.
Logstash input config exemple:
jmx{
	//Required
    path => "/apps/logstash_conf/jmxconf"
    //Optional, default 60s
    polling_frequency => 15
    type => "jmx"
    //Optional, default 4
    nb_thread => 4
  }

json jmx config exemple:
{
  //Require: jmx listening host/ip
  "host" : "192.168.1.2",
  //Require jmx listening port
  "port" : 1335,
  //Optional the username to connect to jmx
  "username" : "user",
  //Optional the password to connect to jmx
  "password": "pass",
  //Optional, Used as the base of the metric name. If not set use
<host>_<port>
  "alias" : "test.homeserver.elasticsearch",
  //List of JMX metrics to retrieve
  "queries" : [
    {
      //Required: The object name of Mbean to request
      "object_name" : "java.lang:type=Memory",
      //Optional: Use this alias in the metrics value instead of the
object_name
      "object_alias" : "Memory"
    }, {
      "object_name" : "java.lang:type=Runtime",
      //Optional: Set of attributes to retrieve. If not set retrieve
all metrics available on the configured object_name.
      "attributes" : [ "Uptime", "StartTime" ],
      "object_alias" : "Runtime"
    }, {
      //object_name can be configured with * to retrieve all matching
Mbeans
      "object_name" : "java.lang:type=GarbageCollector,name=*",
      "attributes" : [ "CollectionCount", "CollectionTime" ],
      //object_alias can be based on specific value from the
object_name thanks to ${<varname>}.
      //In this case ${type} will be replaced by GarbageCollector...
      "object_alias" : "${type}.${name}"
    }, {
      "object_name" : "java.nio:type=BufferPool,name=*",
      "object_alias" : "${type}.${name}"
    } ]
}
Here is the output generated. Depending to the returned value
number/boolean or other it fullfill a metric_value_number or a
metric_value_string event field.
{
               "@version" => "1",
             "@timestamp" => "2014-02-18T20:57:27.688Z",
                   "host" => "192.168.1.2",
                   "path" => "/apps/logstash_conf/jmxconf",
                   "type" => "jmx",
            "metric_path" =>
"test.homeserver.elasticsearch.GarbageCollector.ParNew.CollectionCount",
    "metric_value_number" => 2212
}

{
               "@version" => "1",
             "@timestamp" => "2014-02-18T20:58:06.376Z",
                   "host" => "localhost",
                   "path" => "/apps/logstash_conf/jmxconf",
                   "type" => "jmx",
            "metric_path" =>
"test.homeserver.elasticsearch.BufferPool.mapped.ObjectName",
    "metric_value_string" => "java.nio:type=BufferPool,name=mapped"
}
CloudTrail logs (de)codec
add custom send_field and IO.popen support to zabbix output
Add missing commas on alter filter documentation
Merge pull request #11 from jbochi/patch-1

Add missing commas on alter filter documentation
Merge pull request #10 from borisyukd/output_zabbix

add custom send_field and IO.popen support to zabbix output
Merge pull request #7 from avishai-ish-shalom/cloudtrail

CloudTrail logs (de)codec
Merge pull request #6 from ashangit/master

Add jmx plugin
Add README. Update JRuby version. Bump version.
Merge pull request #12 from untergeek/1.4.x

Add README. Update JRuby version. Bump version.
Added package building script.
Fixed SSL to have it work.
Fix Makefile to make properly named tarball.
Recommended fixes to build.sh
Allow Jenkins more leeway for builds...
This is omitted by .gitignore now, cleaning it up.
Merge branch '1.4.x' of https://github.com/elasticsearch/logstash-contrib into untergeek-1.4.x

Conflicts:
	.gitignore
Merge pull request #14 from untergeek/1.4.x

Work for 1.4.x being merged into master
enable automatically mapping logstash fields to riemann event fields.
Merge pull request #15 from bpezan/master

enable automatically mapping logstash fields to riemann event fields.
Prepare for version bump