Fix a couple bugs in the old org.tigris authentication callback implementation
in JavaHL, which were exposed by the authn callback changes.

[in subversion/bindings/javahl]
* src/org/tigris/subversion/javahl/SVNClient.java
  (SVNClient.PromptUser1Wrapper.userAllowedSave): Forward the call to the
   prompter, if it supports this method.

* tests/org/tigris/subversion/javahl/SVNTests.java
  (SVNTest.DefaultPromptUserPassword.prompt): Return true, indicating success,
   not false, which indicates cancellation.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1600990 13f79535-47bb-0310-9956-ffa450edef68