Attachment server fails on URLs with diacritics

[loveablelobster]

The Specify attachment server responds with an internal server error if the downloadname param contains UTF-8 diacritics (Specify 6 has no problems with this). So this request will work:

www.example.com/fileget?coll=Our+Whales+&type=O&filename=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.pdf&downloadname=Modtagelse+af+hvaler+1.pdf&token=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

While this will throw an error:
www.example.com/fileget?coll=Our+Whales+&type=O&filename=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.att.pdf&downloadname=Journal+på+sæler+-+vedhæftninger%5CNr.+2%5CVægt+%2B+foderskemaer.pdf&token=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Stack trace for the exmapel above:

Traceback (most recent call last):
  File "/home/specify/web-asset-server/bottle.py", line 856, in _handle
    return route.call(**args)
  File "/home/specify/web-asset-server/bottle.py", line 1716, in wrapper
    rv = callback(*a, **ka)
  File "/home/specify/web-asset-server/server.py", line 114, in wrapper
    result = func(*args, **kwargs)
  File "/home/specify/web-asset-server/server.py", line 104, in wrapper
    return func(*args, **kwargs)
  File "/home/specify/web-asset-server/server.py", line 213, in fileget
    download_name = quote(path.basename(download_name))
  File "/usr/lib64/python2.7/urllib.py", line 1283, in quote
    return ''.join(map(quoter, s))
KeyError: u'\xe5'