add tests for Ascii WEP keys and to test invalid parameters

New tests for 40- and 104-bit Ascii WEP keys and a random assortment
of invalid WEP keys (some of which are commented out because they are
permitted right now).

BUG=none
TEST=run 'em and check they do what's expected

Review URL: http://codereview.chromium.org/3461006
3 files changed