Fix problem in MONTHNUM and add DATESTAMP_EVENTLOG pattern and 

Whilst trying to get Windows Event Log data into logstash I had some problems with the the timestamp format Windows uses.

Taking an example value (the TimeGenerated field provided by the eventlog input):

20131218141650.687853-000

And using:

%{YEAR}%{MONTHNUM}%{MONTHDAY}%{HOUR}%{MINUTE}%{SECOND}

I get a %{MONTHNUM} value of 1, but it should be 12. This is because the MONTHNUM pattern allows for single digit month values. I created a new pattern which removed this flexibility:

MONTHNUM2 (?:0[1-9]|1[0-2])

This, along with the pattern below works as I would expect:

DATESTAMP_EVENTLOG %{YEAR}%{MONTHNUM2}%{MONTHDAY}%{HOUR}%{MINUTE}%{SECOND}

I'm sure there's a better way of implementing this but I think this is a genuine problem.
Moved 'success' message into the begin block so it doesn't get printed if there's an error
Fixes exception when not specifying yamlmibdir

Fixes 'undefined method `empty?` for nil:NilClass exception
Add a RFC2822 compliant date pattern

The pattern is defined in RFC2822 and differs from the one defined in
RFC822:
 http://www.ietf.org/rfc/rfc2822.txt

Example:
 Mon, 20 Jan 2014 18:40:18 +0100
on broken pipes - ie program exit, EBADF can will be used instead of EPIPE. This commit will allow pipe command to be restarted.
Merge pull request #1 from ronnocol/patch-1

Update pipe.rb output - Fix LOGSTASH-1860
Update java

Added support for an "_" in the JAVACLASS and added support for a space in the JAVAFILE expression.

Examples are: "at org.jnp.server.NamingServer_Stub.lookup(Unknown Source)"

This example would have failed without the update.
Add some patterns I found useful in parsing mongo logs.
Fix syntax errors in kv examples

Fix syntax errors in examples for the include_keys, exclude_keys and default_keys config values.
Prefix patterns with MONGO_
Minor updates to elasticsearch output docs
Merge pull request #1108 from jamtur01/esdocs

Minor updates to elasticsearch output docs
Merge remote-tracking branch 'upstream/master'
remove the exec fixing JIRA issue 1931
Merge pull request #1109 from ronnocol/master

FIX for 1931: plugin script doesn't complete
Close LOGSTASH-1933:

Add two (2) new config stanzas to IRC output:

pre_string: Message you want emitted to IRC server before the event text
post_string: Message you want emitted to the IRC server after the event text

[12:32]  <logstash> This is a pre message
[12:32]  <logstash> This is the actual message
[12:32]  <logstash> Tis is a post message

In both cases, they are sent as seperate messages to the IRC server, leaving the
event text unmodified.

(N.B. My 1st real modification to the ruby codebase, so someone who knows ruby
should really validate I did this correctly.)
Modified syntax as per suggestion
Fix the 2yyp typo, and properly attribute post_string to come *after* the event
Merge pull request #1111 from ronnocol/master

Close LOGSTASH-1933:
Plugin script failed because it was trying to gzip -dc ${TARGETDIR}${FILENAME},
This was missing a / between the directory and the filename, so it was trying to
uncompress: /opt/logstash/logstash-1.4.0.beta1/vendor/logstashlogstash-contrib-1.4.0.beta1.tar.gz

Changed to uncompress ${TARGET}, which is defined as: ${TARGETDIR}/${FILENAME}