Add more log for verbose mode - closes #331

Author: aleksandr-m

src/main/java/com/amashchenko/maven/plugin/gitflow/AbstractGitFlowMojo.java

@@ -1382,6 +1382,10 @@ private CommandResult executeCommand(final Commandline cmd,
             throw new MojoFailureException(errorStr);
         }
 
+        if (verbose && StringUtils.isNotBlank(errorStr)) {
+            getLog().warn(errorStr);
+        }
+
         return new CommandResult(exitCode, outStr, errorStr);
     }