Usaco doesn't allow passwords with spaces in them

[Jonathan Hitchcock]

The regex for password in the Usaco plugin is \S+, which won't match passwords with spaces (or any non-\S character) in them.

I suggest (\S.*)$, although this will also break passwords begin with spaces, but those are going to be problematic anyway.

(A quick grep for 'password' in other plugins and a once-over on their regexes probably wouldn't hurt either...)