This change-set does the following:
- It adds two new field to AESCBCPKCS7ModeOpts
to allow to pass an IV or a PRNG.
This gives more control on the generation of the
ciphertexts as described in the JIRA item.

Tests have been added to validate the change-set.

Change-Id: Ibe242e46c25440dbf8a2a384c12da0e52c17e03d
Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>