Add the NYSIIS implementation.

This Apache Commons lang codec implementation was used to to verify
correctness of this algorithm, since it seems there are many
different variants.
Tests for NYSIIS.

This originally used a corpus from the "aspell" dictionary, which
was run through a small program to generate the corresponding
NYSIIS output using the apache commons implementation. I felt
this was overkill for this particular algorithm (unlike that of
double metaphone which is way more complex), so I replaced it with
these simpler cases.