RFR: 8150103: Convert TraceClassPaths to Unified Logging

[Max Ockner]

Hello everyone,
Please review this conversion of TraceClassPaths to UL.

Bug: https://bugs.openjdk.java.net/browse/JDK-8150103
Webrev: http://cr.openjdk.java.net/~mockner/classpath.03/

Summary:  TraceClassPaths flag has been reimplemented using the 
classpath tag with Info level.  TraceClassPaths has been added to the 
logging alias table.
There is some related output that was never guarded by "if 
(TraceClassPaths)", so it has not been included in this conversion.
Testing: jtreg runtime tests. Added basic test case at 
test/runtime/logging/ClassPathTest.java

Thanks,
Max