tls: TLSSocket emits 'error' on handshake failure

Removes branch that would make TLSSocket emit '_tlsError' event if error
occured on handshake and control was not released, as it was never happening.
Addedd test for tls.Server to ensure it still emits 'tlsClientError' as expected.

Fixes: https://github.com/nodejs/node/issues/8803
PR-URL: https://github.com/nodejs/node/pull/8805


Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Fedor Indutny <fedor@indutny.com>