fix a couple of eclipse warnings
clean SnmpPeerFactory; add ReST range support

* get rid of a bunch of pointless constructors in SnmpPeerFactory
* add FileReloadContainer support to SnmpPeerFactory (auto-reloads snmp-config.xml when it changes)
* add range support to the SnmpConfigRestService updates -- PUTs now support giving an IP range rather than just an IP address