About ch 1 ex 4 solution

Hi,

Looking at this solution:
https://github.com/careercup/CtCI-6th-Edition-JavaScript-ES2015/blob/master/src/chapter1/ch1-q4.js

We are missing the case when string is given with upper case characters (which is true for the original assignment - the string given is "Tact Coa"). I'd suggest to use toLowerCase() and update tests, what do you think?
