add json file with local variables and add it to Jade task

Locals is a `json` file that contains any possible local variables that you can use in your build system, pre- and post-processors like Jade or Sass. I think we need to create it for each project.

*And we need provide a tools to interact with `json` like SassyJSON for Sass and for other available in `yeogurt` pre- and post-processors.*