Kfsio library: fix memory leak with SssFilter, by deleting "outer" SslFilter instance from SslFilter::Impl methods where required.
Kfsio library: implement client authentication context clear method to allow to cleanup openssl related objects before invoking ssl filter cleanup method.
Meta server: by default limit delegation end time to the session credentials (X509, kerberos ticket, delegation) end time. Parameter metaServer.clientAuthentication.delegationIgnoreCredEndTime can be used to ignore the session's credentials end time. Implement authentication context clear method, and use this method to cleanup openssl object before invoking ssl filter cleanup. Eliminate extraneous update count comparison with authentication context update.
Chunk server: cleanup openssl objects allocated with authentication contexts before invoking ssl filter cleanup.
Test scripts: by default test with 2 meta server client threads.