Don't cache data: URIs

They bloat the cache by storing themselves twice (key + decoded data).

ui/src/main/java/io/xeres/ui/support/ImageCacheService.java

@@ -63,7 +63,7 @@ public Image getImage(String url)
 	@Override
 	public void putImage(String url, Image image)
 	{
-		if (!isImageCacheable(image))
+		if (url.startsWith("data:") || !isImageCacheable(image))
 		{
 			return;
 		}