Bug 28175: Usability improvements to uploads page

Bug 28175: Usability improvements to uploads page

This patch makes a variety of changes to the uploads page in order to
improve usability:

- Add a toolbar with an "Upload" button so that it can be accessed from
  the upload results or search results views
- On views other than the "main" view, add search forms to the sidebar
  - The search form markup has been modified somewhat in order to make
    it work well in both the sidebar and the main body of the page.
- Show the upload category description instead of the code
- Link the upload category in search results to a search for that
  category

The "enctype" attribute has been removed from the search forms because
it is unnecessary and causes form resubmission errors in some browsers
(Firefox at least).

To test, apply the patch and make sure you have at least one entry under
Authorized values for the category UPLOAD.

- Go to Tools -> Upload.
- Upload a file, adding a category as you do so.
- On the upload results page, test that the "Upload file" button
  returns you to the main upload page.
- On the upload results or search results view, confirm that the "Search
  uploads by category" and "Search uploads by name" forms work
  correctly.
- When viewing upload or search results, confirm that the category
  discription is shown instead of the code. Confirm that the category is
  a link to a search for other files in that category.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>