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.
Add NaN handling config options
input/collectd: Implement handling of NaN values
Add tests for the collectd NaN handeling
input/collectd: Better tagging on NaN

  * Don't overwrite existing tags
  * Allow the user to config the tag to add when a NaN is found
Merge pull request #1 from ronnocol/patch-1

Update pipe.rb output - Fix LOGSTASH-1860
touch up statsd output
Fix percentiles on metrics filter
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_
explain defaults
touch up
Added option to disable certificate validation

If a IMAP-server is using a self-signed certificate, this patch adds a "verify_cert" option to the module that is by default set to true (old behavior), but if set to false it will disable the verification check. The result is that IMAP TLS with self-signed certificate will not crash logstash.
Added option to disable certificate validation