Crypto-NG: cleanup and optimize CRL handling

Crypto-NG: cleanup and optimize CRL handling

Certificate Revokation Lists have gone through several iterations
of logic redesign leading to duplicated code and non-optimal I/O.
Client contexts were loading CRL directly from disk into the
context on every new context creation. Whereas the server contexts
were loading into an OpenSSL STACK_OF structure and adding from
memory instead of disk. This later design is more performant.

* Move the pre-loaded CRL set to Security::PeerOptions and store
  in a std::list structure as LockingPointer which will deallocate
  as needed on shutdwown and reconfigure.
  This depends on trunk rev.14304

* Replace the client context disk I/O with the pre-loaded CRL list

* Add GnuTLS CRL list types. Though at this point GnuTLS does not
  pre-load the CRL files.