install: missing idempotent aspects in install and uninstall

Backup all config files
Removing config and log files when uninstalling
Check OSMLCM_VCA_HOST and OSMLCM_VCA_SECRET are not empty

Change-Id: I375308e6dfca1463a06426557f7a7c4b4499b8d6
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>