Clean up java invocation, support custom Java paths
Clean up java invocation, support custom Java paths

We now only use jstreamit.jar, explicitly providing a classpath and main
class (tuner.RunApp), rather than a separate RunApp.jar.  The javaPath
variable should be a system-level constant somewhere, perhaps in its own
untracked file, as it will vary from machine to machine (e.g. on lanka I
need to use java out of my AFS rather than the java on the PATH).

jbosboom/streamjit,jbosboom/streamjit