Removed CBC ciphers to address CVE-2013-0169 (LUCKY13)

Details:

* This change removes the following CBC ciphers from the default set
  of ciphers in order to address CVE-2013-0169 (LUCKY13):
  - ECDHE-ECDSA-AES256-SHA384
  - ECDHE-RSA-AES256-SHA384
  - ECDHE-ECDSA-AES128-SHA256
  - ECDHE-RSA-AES128-SHA256
  This is done by listing them in the code, i.e. without any way to
  configure that by the user.

Signed-off-by: Andreas Maier <maiera@de.ibm.com>