In the event that `CLASSPATH` does not have an ending ":", the shell
can expand the CLASSPATH globs to be space-separated list of paths/jars,
which is not how the JVM CLI accepts arguments to -cp switch. So
double quote the variable to prevent pattern expansion, and pass the
glob pattern directly to the JVM.
Reviewers: Ismael Juma <ismael@juma.me.uk>