added some common interfaces for media data

java/com.sap.sse.common/src/com/sap/sse/common/media/ImageMetadata.java

@@ -0,0 +1,7 @@
+package com.sap.sse.common.media;
+
+public interface ImageMetadata extends MediaMetadata {
+    public int getWidthInPx();
+
+    public int getHeightInPx();
+}

java/com.sap.sse.common/src/com/sap/sse/common/media/MediaMetadata.java

@@ -0,0 +1,23 @@
+package com.sap.sse.common.media;
+
+import java.net.URL;
+import java.util.Date;
+
+/**
+ * A common media interface for all kinds of media like images or videos. 
+ */
+public interface MediaMetadata {
+    public MimeType getMimeType();
+
+    public URL getURL();
+
+    public String getTitle();
+
+    public Iterable<String> getTags();
+
+    public String getSubtitle();
+
+    public Date getCreatedAtDate();
+
+    public String getCopyright();
+}

java/com.sap.sse.common/src/com/sap/sse/common/media/VideoMetadata.java

@@ -0,0 +1,7 @@
+package com.sap.sse.common.media;
+
+public interface VideoMetadata extends MediaMetadata {
+    public int getLengthInSeconds();
+    
+    public String getThumbnailRef();
+}