brewnit: Grammar update

Signed-off-by: Lucas Bajolet <lucas.bajolet@gmail.com>
brewnit: Moved model entities to model folder

Signed-off-by: Lucas Bajolet <lucas.bajolet@gmail.com>
brewnit: Regen lexer and parser

Signed-off-by: Lucas Bajolet <lucas.bajolet@gmail.com>