If a JRE cannot be found at the location specified by JAVA_HOME or
container.javaHome, the server startup fails and an error message is
displayed.
Update the error message so that the reader realizes that while the
JAVA_HOME and/or container.javaHome might be *set* the value in them
might not be *valid*. An example of when this might be the case is when
the java installation was upgraded and the location changed from:
/Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home/jre
to:
/Library/Java/JavaVirtualMachines/jdk1.8.0_192.jdk/Contents/Home/jre
and while the JAVA_HOME environment variable got update to the new
location, container.javaHome did not and still pointed to the old (and
now invalid) location.
Change-Id: I24e0dc19781920e8901ef8743c847606ebd640ce
436e7b79b2