#1 Implement ability to change passwords

[Michael Lee]

When testing K-Li, it was found that almost no one
changed their passwords. This feature was taken out
before a major code rewrite, for the purposes of saving
space.

However, for a more general release, ability to change
passwords might be needed. It will be considered a low
priority bug unless:

1. I can fit it in without taking up a lot of space.
2. Enough people ask for it.