VCA start_build modified to take into account changes in juju client. OSM...

VCA start_build modified to take into account changes in juju client. OSM installer from source modified to check dependencies before installing

Change-Id: Ic7a6ef5d548a5d8cb0d09c405ba94a094c8c01f9
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>