feat(jobserver): Replace manager_start with SparkLauncher (@bsikander) - this is a pretty big deal to stabilize and extend SJS

feat(jobserver): Create context table (@ecandreev)

feat(jobserver): move data from contexts hash to db (@ecandreev)

feat(jobserver): Add CONTEXT_ID and STATE to the JOBS table (@ecandreev)

feat(jobserver): Introduce supervise mode (@bsikander)

• feat(jobserver): Filter jobs by contextId and multiple statuses
• feat(jobserver): Introduce supervise mode for contexts
• feat(jobserver): Make ActorSystem remote port configurable in Jobserver
• fix(jobserver): Improve resolution of JobManagerActor addresses
• feat(jobserver): Add parameter to ignore akka.remote.netty.tcp.hostname
• feat(jobserver): Make sure akka tcp port is not random
• fix(jobserver): Add timeout for DAO failure testcases
• fix(jobserver): Add documentation and remove unused variable

Updated Python documentation to reference PythonSession (@rfrohock)