Python 3: remove usage of print statements

Change-Id: If044b89a238e9516a17ceb3e0a8f6a64b6c07353
Ensure the pipe path is writable

Have pipebot set a suitable uamsk before creating the fifo. This ensures
that everything else will be able to write to it. Also disable
others from reading it (since they don't need to do this).

Change-Id: Ibf9caa620fd9c9700407ab400018421a4d8f8243