extract and use ICircuitBreakerSettings
add CircuitBreakerDatabaseFactory
remove unused  SynchronousTimeoutHandler
wire up CircuitBreakerDatabaseFactory and SqlCircuitBreakerSettings
make MessageFeed recover from failing to load messages for any given partition
extract IHubOnlyDatabaseFactory to make it easier to reason about consumers of PartitionDbs
make SqlCircuitBreakerSettings and ICircuitBreakerSettings in general easier to use
Merge pull request #72 from daptiv/use-circuit-breaker

Use circuit breaker