When doing snmp, messages would always go to log only, even if the
user was at the confetty cli. Give user access to knowing the error
impacting the query.
Refactor the snmputil to be object oriented to simplify upstream code. Implement
a method to generate a mac address to ifName/ifDescr for a given switch.
On the path to instrumenting network switches, first
we'll add some framework for SNMP. Given that we are
using eventlet and thus we need a patchable SNMP,
we employ PySNMP, despite it being a bit peculiar.
This commit tucks away the oddness and makes it
pretty easy to use for our purposes.
