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.
Merge branch 'issue183' of github.com:willkelly/swift-private-cloud into issue183
Merge pull request #194 from willkelly/issue183

Remove unused snmp configuration (solves issue 183)