Backport: Upload: iron out visual and functional differences between javascript and flash widget

Visual differences:

• Both: Difference in labels
• Both: Selection list stays visible after being emptied.
• JS: no odd/even coloring in list
• Flash: ugly border around browse button after click

Functional differences:

• JS: uploads are not sent as Ajax form post.
• JS: if maxItems=1, autoUpload is always true. If autoUpload=true, maxItems is always 1.
• JS: clearAfterUpload=true is simply ignored.
• Flash: does not respect fileupload.maxItems.
• Flash: browse dialog allows the user to select more files than is configured with fileupload.maxItems.
• Flash: autoUpload=true does not wait for maxItems to be reached.
• Flash: Browse button is not disabled when maxItems is reached

New:

• redraw file selection datatable by updating the datasource unless we exceed the scrollbar threshold and need scrollbars.
• code is jslint compliant