1.7.2
* Jobs-->JobsProgress to track jobs in flight + tests * Tests for rp_ping.Heartbeat * refactor: moved JobScaler.process_job to rp_job.handle_job * refactor: JobScaler distinguishes JobsProgress from JobsQueue * fix: Job should accept arbitrary properties + tests * log and raise the JobScaler.handle_job exceptions * refactor: graceful shutdown of tasks when worker is killed * tests: complete tests for rp_ping