Add initializationOptions to InitializeParams

The `InitializeParams.initializationOptions` has just been added to the
protocol:
microsoft/language-server-protocol#55

Author: kaloyan-raev

io.typefox.lsapi/src/main/java/io/typefox/lsapi/InitializeParams.xtend

@@ -28,6 +28,12 @@ interface InitializeParams {
 	@Nullable
 	def String getRootPath()
 
+	/**
+	 * User provided initialization options.
+	 */
+	@Nullable
+	def Object getInitializationOptions()
+	
 	/**
 	 * The capabilities provided by the client (editor)
 	 */