Persistence better logging and optimization

see commits for details

logging is now quite elegant (and code more elegant too).  at `MASTER` we log this for all persistence:

```
2014-11-06 01:53:24,484 DEBUG b.e.r.PeriodicDeltaChangeListener [brooklyn-execmanager-cPHPyZLD-49]: Checkpointing delta of memento: updating entities=[NginxControllerImpl{id=yj1CnqgS}, TomcatServerImpl{id=jFLN539t}, DynamicWebAppClusterImpl{id=mOp5gagc}, ControlledDynamicWebAppClusterImpl{id=cuPk22K9}], locations=[], policies=[], enrichers=[], catalog items=[]; removing entities=[], locations=[], policies=[], enrichers=[], catalog items=[]
2014-11-06 01:53:24,510 DEBUG b.e.r.p.BrooklynMementoPersisterToObjectStore [brooklyn-execmanager-cPHPyZLD-49]: Checkpointed delta of memento in 15ms: updated 4 entities, 3 locations, 2 policies, 35 enrichers, 0 catalog items; removed 0 entities, 0 locations, 0 policies, 0 enrichers, 0 catalog items
```

at `HOT_STANDBY` you see the following most of the time (much more detail on first 5 rebinds and every 1000th, which is about every ~15m):

```
2014-11-06 01:53:24,221 DEBUG b.e.rebind.RebindManagerImpl [brooklyn-execmanager-IEUSHnfF-1]: Rebinding (HOT_STANDBY, iteration 12) from /tmp/mms-amp-data/master...
2014-11-06 01:53:24,223 DEBUG b.e.r.p.BrooklynMementoPersisterToObjectStore [brooklyn-execmanager-IEUSHnfF-1]: Loaded rebind lists; took 1ms: 7 entities, 3 locations, 2 policies, 48 enrichers, 0 feeds, 0 catalog items; from /tmp/mms-amp-data/master
2014-11-06 01:53:24,292 DEBUG b.e.r.p.BrooklynMementoPersisterToObjectStore [brooklyn-execmanager-IEUSHnfF-1]: Loaded rebind raw data; took 69ms; 7 entities, 3 locations, 2 policies, 48 enrichers, 0 feeds, 0 catalog items, from /tmp/mms-amp-data/master
2014-11-06 01:53:24,467 DEBUG b.e.r.p.BrooklynMementoPersisterToObjectStore [brooklyn-execmanager-IEUSHnfF-1]: Loaded rebind manifests; took 174ms: 7 entities, 3 locations, 2 policies, 48 enrichers, 0 feeds, 0 catalog items; from /tmp/mms-amp-data/master
2014-11-06 01:53:24,533 DEBUG b.e.r.p.BrooklynMementoPersisterToObjectStore [brooklyn-execmanager-IEUSHnfF-1]: Loaded rebind mementos; took 5ms: 7 entities, 3 locations, 2 policies, 48 enrichers, 0 feeds, 0 catalog items, from /tmp/mms-amp-data/master
2014-11-06 01:53:24,570 DEBUG b.e.rebind.RebindManagerImpl [brooklyn-execmanager-IEUSHnfF-1]: Rebind complete (HOT_STANDBY, iteration 12) in 349ms: 1 app, 7 entities, 3 locations, 2 policies, 48 enrichers, 0 feeds, 0 catalog items
```

and all nodes get such entries as this:

```
2014-11-06 01:53:24,371 DEBUG b.m.h.ManagementPlaneSyncRecordPersisterToObjectStore [brooklyn-execmanager-IEUSHnfF-3]: Checkpointed delta of manager-memento in 1ms: brooklyn.management.ha.ManagementPlaneSyncRecordDeltaImpl[nodes: [BasicManagementNodeSyncRecord{nodeId=IEUSHnfF, status=HOT_STANDBY}]]
```

each appears once per second, meaning in happy path neither standby nor master logs too much.

there is some slight hack to prevent rebind over-logging, but i don't think it's too bad!

`trace` level restores full logging
I much prefer 8 character indent for wrapped lines. In general, it makes stand out much clearer that this is not just an indent for the next statement. Most of our other code uses that convention.