Ticket #605 - support TLS 1.1 - adding backward compatibility
    
    Description: commit 88d4beccb9d9f7bb89f5e24c47828d7516ba7ca8 always
    expected the NSS version supporting TLS 1.2. It broke the build on
    the system having the NSS version that only supports TLS 1.1 (and
    older). This patch checks the NSS version and switches the supported
    TLS in ssl.c based upon the version info.
    
    https://fedorahosted.org/389/ticket/605
    
    Reviewed by rmeggins@redhat.com (Thank you, Rich!!)