Adding cluster meta data and saving in etcd

Adding cluster meta data and saving in etcd

As part of this patch, we assign groupNumbers
for the set of clusters which are under anyOf, or
in other words are optional for deployement of
app.
Also refactored the instantiation flow by separating
out the etcd interactions

Issue-ID: MULTICLOUD-1064
Signed-off-by: Rajamohan Raj <rajamohan.raj@intel.com>
Change-Id: I21ece189daf6e6b3a7cfdba5df22d57b3d33ca78