[VOL-5000] VOL-5001 - edits for debugging voltha-prototype problems.

Makefile
--------
  o Disable DISTUTILS_DEBUG, only needed when tracing pip install failure.
  o Added comments and minor cleanups.
  o Added enter/leave banners for targets.
  o Display PROTO_FILES macro to see where the bash -c syntax error problem originated.
  o ls /go/src and java_temp/ to show permissions (local docker issue).
  o Sterile target updated to remove java_temp and addeed
    mkdir helper logic to continue building locally.

tox.ini
-------
   o Community reported people are no longer using python protos so
     begin cleanup by removing old interpreters.

Change-Id: Ia7ae20bb409c9ccfdc2e87fb07491a143eae56da
3 files changed