Began adding words.

This is a first cut at a very verbose mechanism for adding words. Hopefully
there won't be a lot of repeated code when it's all said and done.
Adding real words to the puzzle, vertically.

This is first time that actual letters appear in the puzzle! The
current commit only handles adding words vertically, but this enables
me to implement the logic for checking what the user has entered.
Added .swap to .gitignore.

That's right. I'm doing this in Vim. Vim, FTW!
Removed unused console.log().
The code now checks for valid vertical words.

I created more logic in the GameController to gather the letters
that the user has selected, make it into a word, then pass that word
to the LettersBlock object's isWord() method. In addition to this method,
LettersBlock has been modified to keep track of all of its words.