Logtash logging scaffolding extension

First Maestro "extension" for managing long-running applications' logs.
It provides a wrapper around the execution of the application or service
that will manage its output according to the given parameters, to either
redirect the output to a file, or through pipestash, or both.

Signed-off-by: Maxime Petazzoni <max@signalfuse.com>
Maestro 0.1.6

  - Improved support of backing Docker versions. Docker >= 0.7.6 still
    recommended, and if possible post commit 980000071d.
  - Revamped and extended port mapping syntax, see documentation for new
    possibilities.
  - Extended fullstatus display with individual port status.

Signed-off-by: Maxime Petazzoni <max@signalfuse.com>