Redis connection timeout, health check for jobs, accept a JSON as auth header

• Adds an additionalHeaderJson argument to pass a Stringfied JSON header. Useful for Auth. #75
• Use XCLogParser 0.2.33 that fixed a bug to parse validate command errors #77
• Adds a new Environment variable to the backed that allows to specify a connection timeout to Redis. #70
• Adds a new health check endpoint to check if the jobs can connect to the Redis queue. #70