Improvements to MongoDB replica sets

* Replica set class is Iterable<MongoDBServer>
* Replica set entity sets state to on fire if first server up fails to
  initiate the set
* Logging in MongoClientSupport improved when command result was not ok.
don't create quite so many levels deep of task instances;
effector tasks are now (usually) queueing contexts which means the children are immediately available
misc tidies for how tasks are managed
activities sorted by time by default, and time sort is utc millis (though nice time is rendered)
poll tasks (scheduled tasks) pass the entity context better, have better names, and are transient so they don't clutter the activities view
return json by default for individual sensor and config values; also return json for simple reconstitutable bean types; and remove deprecated use of "Util.prep" js method
fix bug where includedEntities was sometimes passed id as a string and other times passed the object with an id field, causing direct links to specific entities not to load
Sets BasicStartable.locations on start
Merge pull request #1109 from aledsage/fix/BasicStartable-setsLocations

Sets BasicStartable.locations on start
add a sensor for all hosts:port to cassandra cluster
Merge pull request #1106 from ahgittin/feature/cassandra

add a sensor for all hosts:port to cassandra cluster
Add an integration test to check Nginx config template usage
Merge pull request #1110 from grkvlt/fix/nginx-template-default

Add an integration test to check Nginx config template usage
Add accessors for SSL configuration
Add PID file and log file attributes
Add an effector to redeploy static content archive
using backing datagrid: use SetFromLiveMap
added EntityDynamicType.FieldAndValue.toString
InternalLocationFactory tidying
Tidy AttributeMap.NULL marker object

- will be required soon for serializing!