build-sanity failure on centos7 due to rhel6/rhel7 specific changes in build

Centos7 build-sanity is broken due to switching from init.d service to systemd service.
Still need to check if the install is broken (when I checked the tests were halfway through, but no couchbase processes were running).

But definitely we need to co-ordinate this change with QE. They have a large number of tests where the tests use /etc/init.d/couchbase-server to start/stop/retart the server. They all will need to change. I think we should revert the changes now and coordinate with QE and test them separately before merging it. (Sorry, I reviewed the change, but didn't realize the impact then)