Expose the node property validation utility in JavaHL.

* build.conf (private-built-includes):
   Added org_apache_subversion_javahl_util_PropLib.h.

[in subversion/bindings/javahl/src/org/apache/subversion/javahl]
* SVNUtil.java (SVNUtil.canonicalizeNodeProperty): New static methods.
* util/PropLib.java (PropLib): New class.

[in subversion/bindings/javahl/native]
* org_apache_subversion_javahl_util_PropLib.cpp: New.
   Native implementation of class Proplib.

[in subversion/bindings/javahl/tests/org/apache/subversion/javahl]
* UtilTests.java (UtilTests.testValidateProp): New test case.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1538133 13f79535-47bb-0310-9956-ffa450edef68