Add start-wan-join, retry-wan-join and related configuration options and commandline options
Added HTTPS support via a new HTTPS Port configuration option similar to the HTTP Port.
Added RPCServerMapper to allow external program to choose remote DC server to target
Change names to StartJoinWan, RetryJoinWan etc
Moved TLS Config stuff to tlsutil package
consul.Config() helper to generate the tlsutil.Config{} struct, 30 second keepalive, use keepalive for HTTP and HTTPS