Bug 16529 - Clean up and improve upload template

Bug 16529 - Clean up and improve upload template

This patch makes some fixes and improvements to the template for Tools
-> Upload, including markup corrections, removal of 'onclick,' and
conversion of some links to styled buttons.

To test, apply the patch and go to Tools -> Upload.

- Confirm that uploading a file works correctly.
- Confirm that clicking 'Cancel' during a file upload works correctly.
- Search existing uploads.
  - Confirm that the 'Download' and 'Delete' buttons look correct and
    work correctly.
- In Administration -> MARC bibliographic framework, choose a
  framework and configure a tag subfield to use the upload plugin.
- Create or edit a bibliographic record using the framework you
  modified.
- Click the tag editor icon next to your modified subfield to trigger
  the pop-up window with the upload form.
  - Confirm that this window has a layout which is adjusted for the size
    of the window.
  - Confirm that uploading and selecting files from this window works
    correctly.

Signed-off-by: Rocio Dressler <rocio@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>