Burnin script logs better output

[iLLiCiTiT]

Changes

• Changes in pype.lib._subprocess

  • all changes should be backwards compatible
  • it is possible to pass logger object (handy in pyblish plugins)
  • Popen subprocess sdterr use subprocesss.PIPE instead of subprocesss.stdout to be able separate them from process.communication()
  • returns whole output of executed process, concatenated stdout and stderr
  • raises RunTimeError instead of ValueError if subprocess ends with nonzero returncode
  • is logging whole stdout at once and stderr at once, instead of line by line
    • line by line spams MongoDB and it is easier to read output from single
    • stdout is logged as debug level
    • stderr is logged as warning level

• ExtractReview & ExtractBurnin plugins

  • are using new changes in _subprocess and are passing logger to it so they do not have to care about logging output

• burnin script

  • removed loglevel from ffmpeg command so whole output from ffmpeg is accesible
  • output of ffmpeg process is actually catched and printed

resolve #640