levels	Pathnames of levels to include in the asset bundle.
locationPath	Pathname for the output asset bundle.
target	Runtime platform on which the asset bundle will be used.

Returns
string String with an error message, empty on success.

Builds one or more scenes and all their dependencies into a compressed asset bundle.

The scene AssetBundle can be built for any target platform and always creates a single compressed unity3d file.

The scene can be downloaded and loaded using the WWW class. You can use WWW.LoadFromCacheOrDownload to cache the downloaded scene after it has been downloaded.

	// Build a streamed unity3d file. This contain one scene that can be downloaded
	// on demand and loaded once its asset bundle has been loaded.
	@MenuItem ("Build/BuildWebplayerStreamed")
	static function MyBuild(){
		var levels : String[] = ["Assets/Level1.unity"];
		BuildPipeline.BuildStreamedSceneAssetBundle( levels, "Streamed-Level1.unity3d", BuildTarget.WebPlayer); 
	}

When downloading the built compressed file, you need to call WWW.assetBundle in order to make the scene available to the Application.LoadLevel() and Application.LoadLevelAdditive() functions.

	function Start () {
		// Download compressed scene. If version 5 of the file named "Streamed-Level1.unity3d" was previously downloaded and cached.
		// Then Unity will completely skip the download and load the decompressed scene directly from disk.
		var download = WWW.LoadFromCacheOrDownload ("http://myWebSite.com/Streamed-Level1.unity3d", 5);
		yield download;
		
		// Handle error
		if (download.error != null)
		{
			Debug.LogError(download.error);
			return;
		}
		
		// In order to make the scene available from LoadLevel, we have to load the asset bundle.
		// The AssetBundle class also lets you force unload all assets and file storage once it is no longer needed.
		var bundle = download.assetBundle;
		
		// Load the level we have just downloaded
		Application.LoadLevel ("Level1");
	}