Drop old platforms (EL 6 and Ubuntu 14), C++11 minimum
Drop old platforms (EL 6 and Ubuntu 14), C++11 minimum

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor