SNMP: Fix Long return types for 64 bit equivalent in SNMP

When a Long value was passed in to the SNMP Adapter, there was no option to convert this to a <literal>Counter64</literal> type but only as <literal>Gauge32</literal>. This caused the return value to be of the incorrect type 32bit and not 64bit. The JVM argument <parameter>-Djboss.snmp.use64bit</parameter> is now available. It can be used to specify that 64bit data types should be returned by the SNMP adapter. Usage <parameter>-Djboss.snmp.use64bit=true</parameter>. The default value is <literal>false</literal>. When set, all Long types are returned as 64bit values. For backward compatibility the default value is <literal>false</literal> so existing setups will not change when a later version of the code is used.