Adjusted tests for the dataType usage.

Updated jQuery for the test page.
Allow reenabling the submit button in the submit callback. Closes #2639
Updated Gallery requirement.
Updated package versions.
Merge branch 'master' into gh-pages
Merge branch 'master' of https://github.com/blueimp/jQuery-File-Upload
Merge branch 'gh-pages' of https://github.com/blueimp/jQuery-File-Upload