Tweet once per day, with a Game of the Day

This removes the fragments.txt file (filled with fragments from
Scribblenauts games) in favor of receiving the Word of the Day from
Wordnik's API. So begins our epic refactor of storing games in a
database with each word mapped to its part of speech, giving us the
ability to better replace _random_ words in the game's title with an
appropriate word from Wordnik.

Signed-off-by: David Celis <me@davidcel.is>