updating images to include json icon and blank icon (for future file types)
updating upload page to include new json-load icon (and re-order load options based on stability)
Merge pull request #9 from erimille/feature/json-icon

pull request to include json icon for new file upload
If Akara throws a 500 no message is set. Check for this possibility on the front-end and show an error screen accordingly. Fixes #2328.
Merge pull request #10 from wamberg/feature/firefox_mq_error

Editor page not displaying errors for mismatched datasource types
merging from upstream/develop