Remove LEGAL file
Fix perfdata to comply with perfdata UOM definition
NEWS: Add warning regarding check_mrtgtraf change

Closes #1296.
check_snmp: Add thresholds to performance data
NEWS: Mention check_snmp's perfdata thresholds
Introduce support for SNMPv3 context in check_snmp

snmpget already supports using SNMPv3 contexts using the option "-n".
Thus all we need to do is introduce a new argument to check_snmp and
pass the argument on to snmpget using snmpget's option "-n".
Since "-n" is already in use for check_snmp for a different purpose,
we use "-N" instead.
NEWS: Mention new check_snmp option

Closes #1221.
Added perfdata to check_nt. New -l options - seconds|minutes|hours|days.
NEWS: Mention new "check_nt -l" parameters

Closes #1253.
check_ssh: change warning to critical for protocal/version errors

It makes more sense to exit critical if a explicit version/protocol is requested. This
would also be more consistent with other plugins. Other string matching plugins like
check_snmp or check_http exit critical if the result does not match.

Signed-off-by: Sven Nierlein <sven@nierlein.de>

Closes #1268
Adding a warning for raising to CRITICAL for protocal/version errors of check_ssh