0.5.0 Release Candidate 5

Changes:

• Handle ffmpeg restarts in the camera subprocess to prevent zombies
• Restart the detection process if it gets stuck
• Switch the detection process to use a queue and the plasma store to avoid locks
• Update the benchmark script to run detection the way frigate does
• Allow the mqtt password to pull from env vars

Docker image is available with docker pull blakeblackshear/frigate:0.5.0-rc5