discovery: don't cache AJAX requests
discovery: don't cache AJAX requests

When pressing the back/forward buttons in Chrome it sometimes returned a
JSON response for the HTML version. To avoid this we can:

- Be more explicit and only allow JSON responses for requests ending with
  ".json" (rails convention), while changing the routes file to default
  to html.
- Simply instruct jQuery to disable caching.

The second option has been used, since it's simpler.

bsc#103174

Signed-off-by: Miquel Sabaté Solà <b4d70704b9e7df580cab34510621dbd0aacb2dfd@suse.com>

ereslibre/velum,vitoravelino/velum,kubic-project/velum,vitoravelino/velum,ereslibre/velum,vitoravelino/velum,MaximilianMeister/velum,kubic-project/velum,MaximilianMeister/velum,vitoravelino/velum,kubic-project/velum,ereslibre/velum,kubic-project/velum,MaximilianMeister/velum,ereslibre/velum,MaximilianMeister/velum