Refactoring delegate tools to use static methods similar to apitools

I saw that in the delegate tools several variables  such as "JSON_COMMENT", "REQUIRED_METHOD_KEYS" , "GET_VERSION_FIELDS" are defined as class variables and then used as instance variables. Consequently, some methods which are meant as utils can not be defined as static. Therefore, in this pull request, these variables are used as class variables (since they were intended to), and some methods are converted to static methods. However, one variable namely "STATIC" is changed a lot inside the instance method so to avoid confusion, I have added it as an instance variable. Still, I think it should be used as class variable as it's value is defined once and never changes.

This pull request aims to close #2