sslutils: expire time in local timezone format

Just turning attached patch of github issue #840 into a push request.
(Closes #1188 and #840)
Even closes #975, #976, #977, #382 and #1161.
check_snmp: small improvement by anonymous submission

- response should not start with the delimiter
- OID response value taken into account

Closes issue #1029
Closes push request #1173