re-enable the permission check for SetSyngroupSpec

The check that the caller of SetSyncgroupSpec has the
Admin ACL was removed since only syncbase servers had
the Admin permission. This CL re-enables that check
and changes the featuretests syncbase server blessings
to be client-based.

This CL makes it so that the clients all have blessings
of root:o:app:client:c%d and the syncgroup acls are set
to name specific clients. The servers are all configured to
have the blessings of all the clients, e.g.

root:o:app:client:c0,root:o:app:client:c1,root:o:app:client:c2,root:o:app:client:c3,root:o:app:client:c4

MultiPart: 1/2
Change-Id: I3bd87298a5a2a526e3c3028abb0c7f02fc0c7083
7 files changed