Remove unused snmp configuration (solves issue 183)

	Remove uused snmp configuration (solves issue 183) …
We are not using snmp to monitor our private cloud installations, so
we do not need to install and configure snmp.

* Removed snmp attributes

* removed snmp templates

* removed snmp resources from base.rb

* removed snmp.rb

* UPGRADING.md already updated to document this change.