Add options to include user defined modules during build process

[raj-vlabs]

We want to give the developers the option to add js/css files into the auto-generated pages. We already use this functionality on our plugins where we specify the js modules.
They should be able to add the option on the page section on the experiment descriptor and while building the page the module should be added to the file.
This should solve some of the LaTeX rendering issues and will be a generic solution as we build support for different features into the framework.