add numeric to bool conversion

[alu]

Add support numeric value to bool conversion

Bool value be expressed as numeric value in MySQL.

Add support ToDato, ToTableName, ToColumnNames to borrowed field contained struct

We need insert values with borrowed value because we do not want to clone String.
For example.

fn insert(mut em: rustorm::EntityManagerMut, message: &str) {
    #[derive(Debug, ToDao, ToTableName, ToColumnNames)]
    struct Row<'b> {
        message: &'b str,
    };

    em.single_insert(&Row { message }).unwrap();
}

[ivanceras]

Thanks for this PR. I'll try to find some time later tonight(maybe) to merge this.