Load handler.config

Resolved most of the issues stated in earlier pull request feedback 
Added Error Handling module 
Multiple things
* Define `MaxServicePool` as a constant in the class
* Here you are assuming that the key will be there always, what if key is not there. Perform `null` check.
* You again assumed that the value for `MaxServicePool` in config will be a number, by mistake if it is not your application will crash. User `int.TryParse`
* Why not have a variable to hold the number of max service pool so that you can use it in above and below line.