This commit, intruduces changes to the current behavior of the "make cleandocker" command.
From now on, an extra parameter must be given in order to delete the persistent volumes, which up until now was done by default. The new command which represents the old behavior (deleting all artifacts created from the docker composition) is "make pv=true cleandocker".
Signed-off-by: Jovan Kostovski <chombium@gmail.com>