logstash-filter-phpunserialize - Contribution Logstash Filter Plugin

Hi,

Php applications sometimes store data in serialized strings `i:123;` `a:1:{s:6:"elem 1"`...

I wrote a filter plugin to convert these _esoteric_ strings to hash.

I followed the [guidelines](https://www.elastic.co/guide/en/logstash/2.4/_how_to_write_a_logstash_filter_plugin.html) up to the point you suggest to create an issue in the elastic/logstash repo to introduice my plugin.

Source code can be found on [github](https://github.com/PascalNoisette/logstash-filter-phpunserialize) and a first release can be downloaded on [rubygems](https://rubygems.org/gems/logstash-filter-phpunserialize)

Regards,
Pascal Noisette