fix password update for JDBC Auth Provider

• Acceptance Test - Add?:

  No

reported at: http://www.igniterealtime.org/community/message/193207

As for the fix, I'd fixed the part which: "When using JDBCAuthProvider instead of DefaultAuthProvider, the Update Password feature fails due to wrong JDBC API call i.e. executeQuery on UPDATE queries, in the source code."

patch is just a few lines, but probably needs revision by someone