build: release-javadoc: Exclude omero client jars

These jars break with javadoc from java 1.7 due to containing
source code as well as classes.  The reasons why this occurs
are not clear, but excluding them works around the immediate
breaking of the build.  The breakage occurs with the Ice 3.5.1
jars, but given that the 3.5.0 (and other) jars also contain
essentially similar content, it's not clear what the trigger
for the breakage is.  It could be a javadoc bug.