fix improper call to InstanceDeleter#delete_instances

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
update assembler spec to use instance_double

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
add debug log to note that there are no unneeded instances/vms to delete

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
refactor assembler spec to use lets

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
use instance_double for cloud double

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
convert more deployment plan spec to use instance_double

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>