Fixes to DNS support in EUCA-6379

- Recursive DNS returns CNAME records in the correct order.
- Recursive DNS always returns a populated Authority and Additional section.
- Property names adjusted to account conflict in displayName handling.
- euca-describe-properties properly shows descritptions when passed -v|--verbose flag.
- Adjusted properties with their descriptions are:

 clc 420 > euca-describe-properties experimental.dns -v
PROPERTY        experimental.dns.enabled        true
DESCRIPTION     experimental.dns.enabled        Enable pluggable DNS resolvers.  Note: This must be 'true' for any pluggable resolver to work.  Also, each resolver may need to be separately enabled.See 'euca-describe-properties experimental.dns'.
PROPERTY        experimental.dns.recursive.enabled      true
DESCRIPTION     experimental.dns.recursive.enabled      Enable the recursive DNS resolver.  Note: experimental.dns.enable must also be 'true'
PROPERTY        experimental.dns.services.enabled       true
DESCRIPTION     experimental.dns.services.enabled       Enable the service topology resolver.  Note: experimental.dns.enable must also be 'true'
PROPERTY        experimental.dns.split_horizon.enabled  true
DESCRIPTION     experimental.dns.split_horizon.enabled  Enable the split-horizon DNS resolution for internal instance public DNS name queries.  Note: experimental.dns.enable must also be 'true'