Remove ntp-server in favor of ntp recipe

Now that the ntp recipe excludes itself from the list of possible
management node ntp server results, there's no need for a separate
recipe. This allows the admin node to use the swift/ntp/servers
attribute like the other node types; either via environment attributes
or node specific attributes.
admin-server no honors mail smarthost setting

Like the previous mail fixes, the admin-server now honors and uses the
mail smarthost attribute if set in environment/node attirubutes. The
admin lookup logic is now in the mail recipe and it also ignores the
search result if the ip is itself.

Fixes swift-private-cloud/issues#171
Merge pull request #173 from claco/ntp-relay-fixes

Merged automatically by jenkins after successful build test