Java8

Allow connection to some servers when using Java 1.8 client side. see https://trac.openmicroscopy.org.uk/ome/ticket/12339

To test:
 * Make sure that Java 8 is used.
 * try to connect to various servers: localhost, trout (develop), or Windows server

if testing this on a Mac opening the Insight client from the Desktop uses the default system java even if you've installed a more recent java, so to test this you should download the Linux client package and use the scripts from the command line.

General question: Do we also want to adjust ```client.cpp```, ```client.py``` etc.?