Adds TLS/SSL support.

Option added to run integration tests over secure mode, details
are in the comments of ITestBase
Tiny logging change.

I forgot to take this out.
Re-did example certs, added override

Example certs are now good for 10 years, and you can
override with -Dcom.basho.riak.security.cacert

Also fixed RiakMessageCodes names for the auth messages; I had
left the Rpb prefix on them. When we switch to including the
class from the riak_pb jar they'll all match now.
Merge pull request #371 from basho/add-security-support

Adds TLS/SSL support.