Default snmp to less verbose logging

Default snmp to less verbose logging

Currently we just use what puppet-snmp provides in terms of defaults.
This means that currently every single snmp query gets logged with
the following:
May 15 10:51:30 centos.localdomain snmpd[5159]: Connection from UDP: [127.0.0.1]:57799->[127.0.0.1]:161
May 15 10:51:30 centos.localdomain snmpd[5159]: Connection from UDP: [127.0.0.1]:57799->[127.0.0.1]:161
May 15 10:51:32 centos.localdomain snmpd[5159]: Connection from UDP: [127.0.0.1]:50566->[127.0.0.1]:161

The reason is that we use '-LS0-6d' as the default content for
/etc/sysconfig/snmpd:
https://github.com/razorsedge/puppet-snmp/blob/master/manifests/params.pp#L322

This default means that we are logging from 0 (LOG_EMERG) to 6
(LOG_INFO). The above messages bring nothing in a default installation
and only spam the log files, so let's lower the upper log level to 5
(LOG_NOTICE) by default, so we properly do not see every single query in
the logs. We add an option so the operator can still configure the
desired log level via a Heat parameter.

Change-Id: I8d3dfdb4d549cd27131346fc477755ad72313449