in anagram_test, a "BANANA" is not a "banana"

I noticed several time that people's solution to this problem don't
include this fact. I think it should.
It also makes the problem more interesting: how to best organize
the code, to avoid using the lower-case function  everywhere in the
code, while keeping it readable.
Merge pull request #12 from mascip/master

in anagram_test, a "BANANA" is not a "banana"