Start development Key seed id from 1 to prevent `Couldn't find Key with id=0` crash on MySQL.

If it starts from `0`, then `bundle exec rake gitlab:setup` gives:

    == Seed from /home/git/gitlab/db/fixtures/development/11_keys.rb
    Couldn't find Key with id=0
    [exception trace and exit error]

for the **MySQL** database only.

Starting from 1 works for both MySQL and PostgreSQL.

Probably linked to the fact that `id` in MySQL is `auto_increment`, which starts from `1`?