Drop "hide_auth" config value

This was never really used.
Drop allow_account_management

The old code resulted in to the (save) default anyway. I don't think we
want to parameterize this currently. Most (if not all) customers want to
use keystone-based auth. For that, swift auto-creates account DB
entries.
Drop "group" configurable

This never existed, the code in swift.common.util:drop_privileges asks
the Unix password database for the group of "user".
Clarify string for delayed_auth
Minor cleanup
Fix 002_add_ceilometer_middleware.rb

It got broken because the middleware got removed later on, so accessing
ta["middlewares"]["ceilometer"]["enabled"] raised an exception.
Merge pull request #190 from vuntz/saschpe

Small cleanups
Do not fail on storage nodes if rsync of rings fails

This can mean that the ring-compute node is not accessible, that its
rsync service is not enabled or that the ring files are missing.

These errors can only happen if there's an error while applying the
ring-compute role on the ring-compute node, which means that the
proposal will fail to apply anyhow.

However, since the storage role is applied twice, including just before
the ring-compute role, if the ring-compute role fails to apply, then we
will hit this error and we will not be able to get the ring-compute role
re-applied. And therefore we will be stuck here.

For the same reason, we now only start the services if the relevant ring
file is present.

Part of https://bugzilla.novell.com/show_bug.cgi?id=861089
Merge pull request #193 from vuntz/fix-migrations

Fix 002_add_ceilometer_middleware.rb
Remove hardcoded path to certificate & key
Merge pull request #197 from vuntz/no-hardcoded-cert

Remove hardcoded path to certificate & key
Merge pull request #195 from vuntz/missing-ring

Do not fail on storage nodes if rsync of rings fails