(NETDEV-17) Remove snmp_{protocol,location,contact} types

In preparation for consolidating the management of these resources under
the `network_snmp` type.
(NETDEV-17) Add network_snmp type

This patch adds the network_snmp type as recommended by our partners.
This type consolidates the information from the previous location,
contact, and overall enable types.
Merge branch 'nd17_snmp_rename'

* nd17_snmp_rename:
  (NETDEV-17) Add network_snmp type
  (NETDEV-17) Remove snmp_{protocol,location,contact} types