Add support for init parameters for module servlets

Currently a module developer can't define init parameters for their servlets, the following needs to be done:

• Update the ModuleParser to read servlet init parameters
• Add init parameters field to ModuleServlet class and Implement getInitParameter(String) and getInitParameterNames() methods
• Update the dtd for config files to support init params for servlets

Alternatively

I assume this MIGHT be solved by upgrading to servlet API 3 which supports web fragments and annotated servlet classes which would mean we can get rid of this custom code for handling module servlets and let it happen magically in the new way