Base64 implementation using Bouncycastle

:tada: 

Hi my friend, commons-code was too verbose and over-engineered, so the best alternative was to extract the encoder from Bouncycastle, props ( http://www.bouncycastle.org/licence.html) already added. 

If we opt in favor of bouncycastle as a crypto lib, in the future will be possible to remove the encoders. For now, I'll try to keep it simple.