tcurl: add support for ssl and raw output
    
    At first, this patch separates curl_easy handle from the multi-handle
    processing and makes it encapsulated in custom tcurl_request structure.
    This allows us to separate protocol initialization from its asynchonous
    logic which gives us the ability to set different options for each
    request without over-extending the parameter list.
    
    In this patch we implement options for peer verification for TLS-enabled
    protocols and to return response with body and headers together.
    
    Reviewed-by: Simo Sorce <simo@redhat.com>
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>