voting-server: add database/schema.sql
voting-server: add database/schema.sql

Signed-off-by: Nuno Azevedo <8c1e4f9df2ead62a44323c12422702b1d8dd9c90@gmail.com>

joaolrpaulo/eletronic-voting-system,joaolrpaulo/eletronic-voting-system,joaolrpaulo/eletronic-voting-system