RFR: CODETOOLS-7902273: Move away from the local j.u.Properties copy - episode 1, make it a stateless utility class

[dmitry.bessonov at oracle.com]

Please review a fix to make the first step away from a local copy of 
j.u.Properties class

With the fix com.sun.javatest.util.Properties class doesn't extend 
Hashtable, unused instance methods removed, one static utility method 
added to serve client code.

JBS: https://bugs.openjdk.java.net/browse/CODETOOLS-7902273
Webrev: http://cr.openjdk.java.net/~dbessono/7902273/webrev/


dmitry