Separate the mesos-containerizer binary into a static binary, which only depends on stout

The mesos-containerizer binary currently has three commands:

• MesosContainerizerLaunch
• MesosContainerizerMount
• NetworkCniIsolatorSetup

These commands are all heavily dependent on stout, and have no need to be linked to libprocess. In fact, adding an erroneous call to process::initialize (either explicitly, or by accidentally using a libprocess method) will break mesos-containerizer can cause several Mesos containerizer tests to fail. (The tasks fail to launch, saying Failed to synchronize with agent (it's probably exited)).

Because this binary only depends on stout, we can separate it from the other source files and make this a static binary.