ubuntu 14.04: install software-properties-common
ubuntu 14.04: install software-properties-common

We can't assume that `add-apt-repository` exists,
let's try to install it by apt.

Signed-off-by: Amos Kong <eb01d8f828a6c9a20be4534e72e049aaf41503df@scylladb.com>

scylladb/scylla-artifact-tests,lmr/scylla-artifact-tests,scylladb/scylla-artifact-tests