Added QAsn1Element

This element can be used for backends that do not offer all the
information that is needed when implementing a ssl certificate backend.
WinRT and the SecureTransport lack functionality in this area for
example.

The sources and tests are added for ssl and openssl configurations in order
to be tested. The condition for adding these can be changed as soon
as they are used by an actual implementation

Change-Id: I2b836133105afdc178bf3b1ee7d732bea069effa
Reviewed-by: Andrew Knight <andrew.knight@digia.com>