Allow both host and hostname options in constructor

Change-Id: Id45dcf6b3bfa39e06f761a6037edd628bafe524e
Reviewed-on: http://review.couchbase.org/40999
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>