fuel, armband: Remove SALT_MASTER_IP param

fuel, armband: Remove SALT_MASTER_IP param

Fuel@OPNFV mcpcontrol network (equiv to old admin/PXE net) has been
configured to use 192.168.10.0/24 during E release cycle.
However, due to overlapping with Ericsson-pod1 networks, we decided
to re-use the old CIDR Fuel used before E release (10.20.0.0/24).

This allows reusing the INSTALLER_IP param instead of recently added
SALT_MASTER_IP param.

Current change refactors all usage of SALT_MASTER_IP in favor of old
INSTALLER_IP, thus reducing complexity and providing a familiar env
to leagcy Fuel users.

JIRA: FUEL-285

Change-Id: I1e89cca08ce4cb9bf3a82a06043c91ee26aa0794
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>