Merge pull request #1097 from sjcorbett/mongodb-tweaks

Small improvements to MongoDB replica sets
collect more sensors for mongo, and add a ResilientMongoApp; also let the default isRunning check fail more quickly (so failures are picked up sooner, as isRunning is done on restart, and clouds which black-hole ssh will cause the max timeout to occur, time num ssh retries (4) ); and also misc tidies to other items (mainly deprecation)