Edit/create memcached.conf template resource

The upstream memcached cookbook is not quite ideal for wrappering as it
declares resources dynamically rather than using only_if style platform
checks. As such, we clone of the conf on ubuntu would cause memcached
restarts on every run.

Fixes rcbops-cookbooks/swift-private-cloud#195
Merge pull request #200 from claco/issue-195

Merged automatically by jenkins after successful build test