lib.sh: Extend wait_for function to catch no resp

lib.sh: Extend wait_for function to catch no resp

wait_for function should be able to also check for minions that did
not return or not respond, in addition to the return code.
To keep it backwards compatible, condition the new check on the max
attempt number being specified in decimal format (e.g. '10.0' unlike
old '10').

Change-Id: If2512cf9121cdd795638efe7362ef0485d4e8d91
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
(cherry picked from commit 3f559299c232bbb7639d02243c95d6256cdf94d4)