Feature: GetJson and GetJson in short codes or other layout files.

I have finished the integration of getJson and getCsv into hugo as far as I think it fits.

I'm not a hugo (and Go) expert of where to put these functions and correct naming of functions and vars.

I would be glad if you can comment on spotted errors, bugs, bad design, etc. or even help me to improve the code more.

All tests and the new tests are passing. Goimports has reordered some import paths.

I have written a blog post about that new feature: [http://cyrillschumacher.com/2014/12/21/dynamic-pages-with-gohugo.io/](http://cyrillschumacher.com/2014/12/21/dynamic-pages-with-gohugo.io/)

There is not yet any official documentation because I want to get the code right. I think once this feature is merged as a hidden feature into hugo and some people tested it in the wild with no given complaints I will write the docs.

Looking forward for a successful merge :-)