Keras Rewrite

Rewrote the original project in keras instead of pybrain.

New version offers better raps, and more adjustable performance (e.g. control over syllables, etc.)

New format for saved networks (.rap files) and for the rhymes (.rhymes files) are introduced instead of the folders used in previous versions.

Fixed issues with the Markov chain and users getting stuck on "writing the raps word by word"