Changes poms that require JDK jars to activate dependencies via profiles based on the jars existence

Previously it was activated based on OS name/family values instead. That created two dependencies, one
 on the OS name/family and the other on the file itself. This caused problems with the JDK6 to 7 transition
 for MacOS X, since the location of the JDK and libraries change between those two versions.
 The solution is to activate the dependency on the file's existence, since that is measureable on all
 JDK versions in an OS independent way.