Add Example code or writing Plate data to ome-tiff.

Add Example code or writing Plate data to ome-tiff.
```java.nio.file.FileSystems``` was introduced in Java 1.7 (http://docs.oracle.com/javase/7/docs/api/java/nio/file/FileSystems.html).

If I do ```javac -source 1.6 FileExportSPW.java```, then I see this: http://gist.github.com/anonymous/2de48ec07fd9e973f7cd

Can the 1.7-specific things please be removed, given that 1.6 is the minimum everywhere else?