Missing category filter for jobs short-code with categories argument

1533443-zen

If you create something like this: `[jobs categories=superhero-job]`, it'll result in the following page:
http://cld.wthms.co/xbYoHV


but it'd be better if it results in this form: http://cld.wthms.co/0Pt9jJ


Reproduce the `[jobs categories=superhero-job]` shortcode case and compare its output with the expected example linked in the issue. Trace the jobs shortcode entry point and category-filter handling; done means the categories argument produces the filtered form shown in the second screenshot without changing the default shortcode output.

Written by the indexing model from the issue text.