ZF-2148: YAML Serialization

Description

Add YAML serialization

Comments

We will defer to an extension if it is present.

As far as I am aware, YAML serialisation within the framework is deferred indefinitely (or that was my interpretation of the review of Zend_Yaml?) so one should rely ultimately on the PECL syck extension or a third party light parser in PHP.

This doesn't appear to have been fixed in 1.5.0. Please update if this is not correct.

This functionality will require a full proposal transitioned through the proposal process.

This issue was implemented in ZF-1.11.