Chek if SNMP is available on the server.

def check_snmp(self):
        """Chek if SNMP is available on the server."""
        # Import the SNMP client class
        from glances.snmp import GlancesSNMPClient

        # Create an instance of the SNMP client
        clientsnmp = GlancesSNMPClient(host=self.args.client,
                                       port=self.args.snmp_port,
                                       version=self.args.snmp_version,
                                       community=self.args.snmp_community,
                                       user=self.args.snmp_user,
                                       auth=self.args.snmp_auth)

        # If we cannot grab the hostname, then exit...
        ret = clientsnmp.get_by_oid("1.3.6.1.2.1.1.5.0") != {}
        if ret:
            # Get the OS name (need to grab the good OID...)
            oid_os_name = clientsnmp.get_by_oid("1.3.6.1.2.1.1.1.0")
            try:
                self.system_name = self.get_system_name(oid_os_name['1.3.6.1.2.1.1.1.0'])
                logger.info("SNMP system name detected: {}".format(self.system_name))
            except KeyError:
                self.system_name = None
                logger.warning("Cannot detect SNMP system name")

        return ret