Subversion: Add vcsTopic

This partially addresses QTCREATORBUG-12929 which is about svn commit no
longer showing output which does include the revision number

Change-Id: I149f1fea05a63cc80625ba5e02c10edbce471e1a
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/subversion/subversionclient.h

@@ -81,6 +81,8 @@ public:
                                                 const QString &userName = QString(),
                                                 const QString &password = QString());
 
+    QString synchronousTopic(const QString &repository);
+
 protected:
     Core::Id vcsEditorKind(VcsCommandTag cmd) const;
     VcsBase::VcsBaseEditorParameterWidget *createDiffEditor(const QString &workingDir,