Script that can be automatically run on start and exit of MongoBooster

Having the ability to run a script on the start and exit of MongoBooster will be very helpful.

1. There may be an initialization that need to happen when MongoBooster is setup (if a .js can be picked to run when MongoBooster turns on) that will help automate that process.
2. Similarly, when MongoBooster exits, there may be a need for cleanup script that can be run (if a .js can be selected to run when MongoBooster exits) that will help automate that process.