Quick fixes for renderer project

Merged Eclipse Webmaster requested to merge github/fork/dbluhm/fix-renderer into next

Created by: dbluhm

Some quick fixes for org.eclipse.ice.renderer. My recent JSON PR had some errors in the persistence template that went uncaught in the proxytest module as tests for persistence aren't implemented yet. In the future, the tests in renderer should probably just be removed but this gets things working again for now.

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