Add configurable etcd storage feature

Plus the option to have etcd on tmpfs (volatile storage) for little
bigger (maybe) speed (NOT FOR PRODUCTION DEPLOYMENT!).

Issue-ID: OOM-2058

Change-Id: I0bbfc4fbae7f6b46e2fae49656437cd6748efd49
Signed-off-by: Petr Ospalý <p.ospaly@partner.samsung.com>
4 files changed