add the required and optional packages for watcher
add the required and optional packages for watcher

There are number of client packages that are required by watcher in
order to function correctly. See

https://opendev.org/openstack/watcher/src/branch/master/watcher/common/clients.py

So add those as requires. Also, ceilometerclient is optional so we add
it as recommends instead.

Change-Id: Icd36642ba4509ac655aaa65c059dd61d763f7b9c

openstack/rpm-packaging,openstack/rpm-packaging