Network: replace neutron check with decorator

Commit a581823ecee286c5c6329c9c373f0fea0b6b729f added in a
validator that would check if neutron was enabled.

It is much cleaner to do this as a decorator. The decorator
here needs to preserve the function signature.

Change-Id: I355e4bcee5e93a7f1459672e10ad7793d2bf8a49
Handle situation when key not memcached

LOG a warning message if the key not memcached successful. This will
happen if memcached module is used but the memcached servers are not
reachable.

Change-Id: Ia3c51fe8fc82060586a014f5cb1083d5695ab455
Closes-bug: 1213660
Merge "Handle situation when key not memcached"
Merge "Network: replace neutron check with decorator"