ISPN-2281 Memcached server to pass flags and version via Metadata

* Added MemcachedMetadata to ship flags and version information.
* Added replace(K, V, Metadata) operation and added tests.
* Fixed bug where ReplaceCommand was not using valueEquivalence to
compare old and new value.
* Created ByteArrayCacheTest to exercise cache operations when
storing byte array key/value instances.
* Added externalizers for all metadata classes.
ISPN-2281 Add compatibility mode for REST and Memcached

* Added compatibility mode XML and programmatic configuration.
* Added REST and Memcached compatibility tests with Embedded
and Hot Rod.
* Add flags to signal operations original in server endpoints,
in particular Hot Rod and Memcached, which allows selecting
the correct type converter according to each server endpoint
requirements.
* Created type converter implementations for Hot Rod, Memcached
and Embedded modes. REST server does not really need it since
it alredy does a lot of type conversion based on content type.
* Enhance type converter interface to allow hooking operation
origins with their corresponding type converter instance, and
enable marshaller to be set in order to help interoperability
between endpoints.