Soft schema-based storage

This JIRA is about storing metadata alongside values. Perhaps encapsulating values as SchematicValues, which could be described as:

  class SchematicValue {
    String jsonMetadata;
    String jsonObject;
  }

Metadata would allow for a few interesting features:

• Extracting of lifespan and timestamp data if manipulated over a remote protocol (REST, HotRod, etc)
• Content type for REST responses
• Timestamps and SHA-1 hashes, useful for for HTTP headers (e.g., ETag, Cache-control, etc.)
• Validation information (may not be processed by Infinispan, but can be used by client libs)
• Classloader/marshaller/classdef version info
• General structure of the information stored
• Reference to the schema for this document
• Storage of older versions