#2176: Use label instead of input button to trigger file upload dialog.

When the file upload dialog is triggered programmatically, it won't trigger the change event when the dialog is closed. Using a label allows the programmatic activation to be handled by the browser itself.
#2176: Simulate :active psuedo-class with js events.
Merge pull request #2227 from openscholar/2176-ie_upload_form

Fix upload form for IE