Added native metadata support.

Metadata.java:
Fixed typo 8k != 8092. The comment was correct though.

In Metadata.h, the new Metadata class is declared in the ns android::media
to limit the chances of conflict with other packages.

The MetadataType in MediaPlayerInterface is gone and moved to Metadata as
an inner typedef.

Similarly the SortedVector<MetadataType> instance have been replace by a
new type Metadata::Filter.

All the keys declared in the java counterpart are also in Metadata.h.

Metadata.cpp:
Contains the implementation of the native metadata packing.

There an associated change in the opencore package that should go in
at the same time as this one.
diff --git a/include/media/PVPlayer.h b/include/media/PVPlayer.h
index 40ccc14..8a66152 100644
--- a/include/media/PVPlayer.h
+++ b/include/media/PVPlayer.h
@@ -19,6 +19,7 @@
 
 #include <utils/Errors.h>
 #include <media/MediaPlayerInterface.h>
+#include <media/Metadata.h>
 
 #define MAX_OPENCORE_INSTANCES 25
 
@@ -53,8 +54,9 @@
     virtual status_t    setLooping(int loop);
     virtual player_type playerType() { return PV_PLAYER; }
     virtual status_t    invoke(const Parcel& request, Parcel *reply);
-    virtual status_t    getMetadata(const SortedVector<MetadataType>& ids,
-                                    Parcel *records);
+    virtual status_t    getMetadata(
+        const SortedVector<media::Metadata::Type>& ids,
+        Parcel *records);
 
     // make available to PlayerDriver
     void        sendEvent(int msg, int ext1=0, int ext2=0) { MediaPlayerBase::sendEvent(msg, ext1, ext2); }