better error message when private key for stunnel SSL is missing (needed by stunnel)
better error message when private key for stunnel SSL is missing (needed by stunnel)

DrXyzzy/smc,sagemathinc/smc,sagemathinc/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc,tscholl2/smc,DrXyzzy/smc,DrXyzzy/smc,DrXyzzy/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc