Option to disable echo of SSH command

Please add an option to disable echo of SSH command to the log. I meaning something like `set +x` does for "Execute shell" build step.

One problem with echoing all commands is that it most of our commands doesn't really contain interesting information. Anything that needs to be echoed is echoed with explicit command.

Another problem is that I echo tags like "[ERROR]" and then search the log for them. If the command itself is echoed then it will be recognized as an error and so I have to use tricks like `echo "[""ERROR] Something"`.